Add .cold. to mangled functions check

gcc8 introduces ".cold." optimization symbols that have arbitrary
trainling numbers in their names just like ".isra." and others.
Add ".cold." to a condition in kpatch_rename_mangled_functions()

Signed-off-by: Artem Savkov <asavkov@redhat.com>

kpatch-build/create-diff-object.c

@@ -825,6 +825,7 @@ static void kpatch_rename_mangled_functions(struct kpatch_elf *base,
 
 		if (!strstr(sym->name, ".isra.") &&
 		    !strstr(sym->name, ".constprop.") &&
+		    !strstr(sym->name, ".cold.") &&
 		    !strstr(sym->name, ".part."))
 			continue;