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

$ go version
1.14.1

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

$ go env
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/wpeng/.cache/go-build"
GOENV="/home/wpeng/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOOS="linux"
GOPATH=""
GOPROXY="https://goproxy.cn,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.google.cn"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build297722647=/tmp/go-build -gno-record-gcc-switches"

What did you do?

`
[wpeng@localhost topsec]$ go mod tidy
[wpeng@localhost topsec]$ go mod vendor
[wpeng@localhost topsec]$ make
sh buildav.sh

github.com/gen2brain/go-unarr

vendor/github.com/gen2brain/go-unarr/unarr.go:6:19: fatal error: unarr.h: No such file or directory
#include <unarr.h>
^
compilation terminated.
make: *** [build] Error 2
[wpeng@localhost topsec]$ ll vendor/github.com/gen2brain/go-unarr/
.appveyor.yml .gitignore .goreleaser.yml .travis.yml LICENSE README.md build.sh go.mod unarr.go unarr_cgo.go
[wpeng@localhost topsec]$ ll vendor/github.com/gen2brain/go-unarr/
total 28
-rw-rw-r--. 1 wpeng wpeng 893 Dec 22 16:27 LICENSE
-rw-rw-r--. 1 wpeng wpeng 2613 Dec 22 16:27 README.md
-rw-rw-r--. 1 wpeng wpeng 1449 Dec 22 16:27 build.sh
-rw-rw-r--. 1 wpeng wpeng 46 Dec 22 16:27 go.mod
-rw-rw-r--. 1 wpeng wpeng 5300 Dec 22 16:27 unarr.go
-rw-rw-r--. 1 wpeng wpeng 1910 Dec 22 16:27 unarr_cgo.go
[wpeng@localhost topsec]$ ll ~/gowork/pkg/mod/github.com/gen2brain/go-unarr@v0.1.1/
.appveyor.yml .goreleaser.yml LICENSE build.sh external/ testdata/ unarr_cgo.go
.gitignore .travis.yml README.md cmd/ go.mod unarr.go unarr_test.go
[wpeng@localhost topsec]$ ll ~/gowork/pkg/mod/github.com/gen2brain/go-unarr@v0.1.1/
total 36
-r--r--r--. 1 wpeng wpeng 893 Oct 27 15:42 LICENSE
-r--r--r--. 1 wpeng wpeng 2613 Oct 27 15:42 README.md
-r--r--r--. 1 wpeng wpeng 1449 Oct 27 15:42 build.sh
dr-xr-xr-x. 3 wpeng wpeng 19 Oct 27 15:42 cmd
dr-xr-xr-x. 6 wpeng wpeng 56 Oct 27 15:42 external
-r--r--r--. 1 wpeng wpeng 46 Oct 27 15:42 go.mod
dr-xr-xr-x. 2 wpeng wpeng 120 Oct 27 15:42 testdata
-r--r--r--. 1 wpeng wpeng 5300 Oct 27 15:42 unarr.go
-r--r--r--. 1 wpeng wpeng 1910 Oct 27 15:42 unarr_cgo.go
-r--r--r--. 1 wpeng wpeng 6894 Oct 27 15:42 unarr_test.go
[wpeng@localhost topsec]$

`

What did you expect to see?

After "go mod vendor", go-unarr should all be copied into my vendor directory.

What did you see instead?

Only the files in Go-unarr are copied, and the subdirectories are not included.