objtool: Query pkg-config for libelf location

If it is not in the default location, compilation fails at several points.

Signed-off-by: Rolf Eike Beer <eb@emlix.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/91a25e992566a7968fedc89ec80e7f4c83ad0548.1553622500.git.jpoimboe@redhat.com

diff --git a/Makefile b/Makefile
index c0a3406..eef3d3f 100644
--- a/Makefile
+++ b/Makefile
@@ -950,9 +950,11 @@
 endif
 export mod_sign_cmd
 
+HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
+
 ifdef CONFIG_STACK_VALIDATION
   has_libelf := $(call try-run,\
-		echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf -,1,0)
+		echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
   ifeq ($(has_libelf),1)
     objtool_target := tools/objtool FORCE
   else