kbuild: Check if linker supports the -X option

The new alternative `gold' linker in recent binutils doesn't support
the -X option. This breaks allyesconfig builds that have
CONFIG_STRIP_ASM_SYMS enabled. Check if the linker really supports
the option using ld-option.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

diff --git a/Makefile b/Makefile
index d04ad67..a3b7770 100644
--- a/Makefile
+++ b/Makefile
@@ -640,7 +640,7 @@
 LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)
 
 ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
-LDFLAGS_vmlinux	+= -X
+LDFLAGS_vmlinux	+= $(call ld-option, -X,)
 endif
 
 # Default kernel image to build when no specific target is given.