community/go: remove set-external-linker.patch

It was pointed out on IRC by kaey that this patch is no longer needed,
make.bash has special handling for Alpine nowadays.

See: https://github.com/golang/go/issues/18243
7 jobs for !4139 with go-no-external-linker-patch in 6 minutes and 12 seconds (queued for 2 seconds)
latest detached
Status Job ID Name Coverage
  Lint
passed #50722
docker-alpine x86_64
lint

00:00:23

 
  Build
failed #50727
docker-alpine ci-build aarch64
build-aarch64

00:03:35

passed #50728
docker-alpine ci-build armv7
build-armv7

00:05:47

passed #50726
docker-alpine ci-build ppc64le
build-ppc64le

00:05:35

passed #50725
docker-alpine ci-build s390x
build-s390x

00:03:34

passed #50724
docker-alpine ci-build x86
build-x86

00:02:37

passed #50723
docker-alpine ci-build x86_64
build-x86_64

00:03:02

 
Name Stage Failure
failed
build-aarch64 Build
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