re PR other/46789 (go configuration with --prefix=/usr pollutes the /usr/lib namespace)

re PR other/46789 (go configuration with --prefix=/usr pollutes the /usr/lib namespace)

	PR other/46789
	PR bootstrap/46812
	* go-lang.c (go_char_p): Define type and vectors.
	(go_search_dirs): New static variable.
	(go_langhook_handle_option): Use version and version/machine
	directories for -L.
	(go_langhook_post_options): Add non-specific -L paths.
	* Make-lang.in (go/go-lang.o): Define DEFAULT_TARGET_VERSION and
	DEFAULT_TARGET_MACHINE when compiling.
	* gccgo.texi (Invoking gccgo): Only document -L for linking.
	(Import and Export): Don't mention -L for finding import files.

libgo: Install .gox files in version and target specific directory.

From-SVN: r167537