objtool: Fix ".cold" section suffix check for newer versions of GCC

With my version of GCC 9.3.1 the ".cold" subfunctions no longer have a
numbered suffix, so the trailing period is no longer there.

Presumably this doesn't yet trigger a user-visible bug since most of the
subfunction detection logic is duplicated.   I only found it when
testing vmlinux.o validation.

Fixes: 54262aa2 ("objtool: Fix sibling call detection")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/ca0b5a57f08a2fbb48538dd915cc253b5edabb40.1611263461.git.jpoimboe@redhat.com

tools/objtool/check.c

@@ -846,8 +846,8 @@ static int add_jump_destinations(struct objtool_file *file)
 			 * case where the parent function's only reference to a
 			 * subfunction is through a jump table.
 			 */
-			if (!strstr(insn->func->name, ".cold.") &&
-			    strstr(insn->jump_dest->func->name, ".cold.")) {
+			if (!strstr(insn->func->name, ".cold") &&
+			    strstr(insn->jump_dest->func->name, ".cold")) {
 				insn->func->cfunc = insn->jump_dest->func;
 				insn->jump_dest->func->pfunc = insn->func;