The files below had conflicts that required manual resolution.
The unresolved conflict in noder.go was just in the import
declaration (trivial). All the other conflicts are in tests
where the ERROR regex patterns changed to accomodate gccgo
error messages (incoming from dev.regabi), and to accomodate
types2 in dev.typeparams. They were resolved by accepting the
dev.regabi changes (so as not to lose them) and then by re-
applying whatever changes needed to make them pass with types2.
Finally, the new test mainsig.go was excluded from run.go when
using types2 due to issue #43308.

	src/cmd/compile/internal/gc/noder.go
	test/fixedbugs/bug13343.go
	test/fixedbugs/bug462.go
	test/fixedbugs/issue10975.go
	test/fixedbugs/issue11326.go
	test/fixedbugs/issue11361.go
	test/fixedbugs/issue11371.go
	test/fixedbugs/issue11674.go
	test/fixedbugs/issue13365.go
	test/fixedbugs/issue13471.go
	test/fixedbugs/issue14136.go
	test/fixedbugs/issue14321.go
	test/fixedbugs/issue14729.go
	test/fixedbugs/issue15898.go
	test/fixedbugs/issue16439.go
	test/fixedbugs/issue17588.go
	test/fixedbugs/issue19323.go
	test/fixedbugs/issue19482.go
	test/fixedbugs/issue19880.go
	test/fixedbugs/issue20185.go
	test/fixedbugs/issue20227.go
	test/fixedbugs/issue20415.go
	test/fixedbugs/issue20749.go
	test/fixedbugs/issue22794.go
	test/fixedbugs/issue22822.go
	test/fixedbugs/issue22921.go
	test/fixedbugs/issue23823.go
	test/fixedbugs/issue25727.go
	test/fixedbugs/issue26616.go
	test/fixedbugs/issue28079c.go
	test/fixedbugs/issue28450.go
	test/fixedbugs/issue30085.go
	test/fixedbugs/issue30087.go
	test/fixedbugs/issue35291.go
	test/fixedbugs/issue38745.go
	test/fixedbugs/issue41247.go
	test/fixedbugs/issue41440.go
	test/fixedbugs/issue41500.go
	test/fixedbugs/issue4215.go
	test/fixedbugs/issue6402.go
	test/fixedbugs/issue6772.go
	test/fixedbugs/issue7129.go
	test/fixedbugs/issue7150.go
	test/fixedbugs/issue7153.go
	test/fixedbugs/issue7310.go
	test/fixedbugs/issue8183.go
	test/fixedbugs/issue8385.go
	test/fixedbugs/issue8438.go
	test/fixedbugs/issue8440.go
	test/fixedbugs/issue8507.go
	test/fixedbugs/issue9370.go
	test/fixedbugs/issue9521.go

Change-Id: I26e6e326fde6e3fca5400711a253834d710ab7f4

…d main function signature

Updates #43308.

Change-Id: I2caff83f304c7e104edda76ac3623cce9fc94a8d
Reviewed-on: https://go-review.googlesource.com/c/go/+/279552
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

This is a port of CL 279424, which didn't make it into master in time
for go1.16. Move it to dev.regabi so that it may be merged.

Notably, this port no longer removes the _InvalidInitSig error code,
instead opting to deprecate it. Now that error codes are 'locked in' for
go1.16, even if their API may not yet be exposed, we should follow the
practice of not changing their values. In the future, code generation
can make it easier to keep error code values constant.

For #43308

Change-Id: I5260b93fd063393d38d6458e45a67e7f9b7426ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/289714
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>