golang: new packages

From golang.org:
The Go programming language is an open source project to make
programmers more productive.

This commit consists of two "parts":

* golang/host: Main Go compiler for host (installed to
  STAGING_DIR_HOST/lib/go-cross), used to cross-compile Go programs to
  be packaged.

* golang (and golang-src/golang-doc): Main Go compiler for on-target
  development. These packages are quite large, but I would expect only
  developers to install these.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

lang/golang/golang/files/go-gcc-helper

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+me=go-gcc-helper
+name=$(basename $0)
+
+case $name in
+gcc)
+	cmd=$GO_GCC_HELPER_CC
+	;;
+g++)
+	cmd=$GO_GCC_HELPER_CXX
+	;;
+*)
+	echo "$me: unknown command \"$name\""
+	exit 1
+	;;
+esac
+
+export PATH="$GO_GCC_HELPER_PATH"
+
+echo "$me: running $cmd $@"
+
+$cmd "$@"