What version of Go are you using (go version)?

$ go version
go 1.13


### What did you do?
mac os upgrade to 10.15 catalina



### What did you see instead?
# runtime/cgo
In file included from _cgo_export.c:3:
/usr/local/include/stdlib.h:134:25: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:134:25: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:134:25: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:135:22: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:135:22: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:135:22: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:136:23: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:136:23: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:136:23: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:139:20: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:139:20: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:139:20: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:141:26: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:141:26: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:141:26: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:141:45: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:141:45: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:141:45: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:142:59: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:142:59: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:142:59: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:142:73: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:142:73: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:142:73: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:141:6: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:141:6: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:141:6: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:147:25: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:147:25: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:147:25: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:147:6: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:147:6: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:147:6: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:156:23: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:156:23: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:156:23: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:157:26: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:157:26: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:157:26: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:157:52: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:157:52: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:157:52: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:158:21: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:158:21: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:158:21: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:158:46: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:158:46: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:158:46: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:160:18: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:160:18: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:160:18: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:161:43: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:161:43: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:161:43: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:161:57: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:161:57: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:161:57: note: insert '_Nonnull' if the pointer should never be null
fatal error: too many errors emitted, stopping now [-ferror-limit=]