Add -fuse-ld=bfd/-fuse-ld=gold support to exec-tool.in

Add -fuse-ld=bfd/-fuse-ld=gold support to exec-tool.in

	PR bootstrap/55552
	* configure.ac (install_gold_as_default): New.  Set to yes for
	--disable-ld or --enable-gold=default.
	(gcc_cv_ld_gold_srcdir): New.
	(gcc_cv_ld): Also check in-tree gold if install_gold_as_default
	is yes.
	(ORIGINAL_LD_BFD_FOR_TARGET): New AC_SUBST.
	(ORIGINAL_LD_GOLD_FOR_TARGET): Likewise.
	* configure: Regenerated.

	* exec-tool.in (ORIGINAL_LD_BFD_FOR_TARGET): New variable.
	(ORIGINAL_LD_GOLD_FOR_TARGET): Likewise.
	(original) [collect-ld && -fuse-ld=bfd]: Set to
	$ORIGINAL_LD_BFD_FOR_TARGET.
	(original) [collect-ld && -fuse-ld=gold]: Set to
	$ORIGINAL_LD_GOLD_FOR_TARGET.
	(dir) [collect-ld && ../gold/ld-new]: Set to gold.
	(fast_install) [collect-ld && ../gold/ld-new]: Set to yes.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@205392 138bc75d-0d04-0410-961f-82ee72b054a4