build-style/go: don't set GOBIN

Go 1.5 doesn't permit our use of GOBIN anymore, breaking
cross-compilation (for details, see
https://github.com/golang/go/issues/9769)

In retrospect, I'm not sure why we set GOBIN in the first place;
GOPATH/bin should suffice.

Closes #2337

common/build-style/go.sh

@@ -14,7 +14,7 @@ do_build() {
 }
 
 do_install() {
-	find "${GOBIN}" -type f -executable | while read line
+	find "${GOPATH}/bin" -type f -executable | while read line
 	do
 		vbin "${line}"
 	done

common/environment/build-style/go.sh

@@ -12,4 +12,3 @@ case "$XBPS_TARGET_MACHINE" in
 esac
 
 export GOPATH="${wrksrc}/_build-${pkgname}-xbps"
-export GOBIN="${wrksrc}/_build-${pkgname}-xbps-bin"

srcpkgs/packer/template

@@ -1,11 +1,10 @@
 # Template file for 'packer'
 pkgname=packer
 version=0.8.6
-revision=2
+revision=3
 replaces="packer-bin>=0"
 short_desc="Create identical multiplatform machine images from a single source"
 maintainer="Andrea Brancaleoni <miwaxe@gmail.com>"
-nocross=yes # temporary hack for #2337
 build_style=go
 hostmakedepends="git"
 license="MPL-2"
@@ -21,7 +20,7 @@ post_build() {
 }
 
 do_install() {
-	find "${GOBIN}" -type f -executable | while read line
+	find "${GOPATH}/bin" -type f -executable | while read line
 	do
 		if [[ $(basename $line) == packer ]]; then
 			vbin $line