Add -fmodules-local-submodule-visibility to MANDATORY_MODULE_BUILD_CFLAGS

to work around build failure introduced in https://reviews.llvm.org/D119036

Author: adrian-prantl

lldb/packages/Python/lldbsuite/test/make/Makefile.rules

@@ -266,7 +266,8 @@ MANDATORY_MODULE_BUILD_CFLAGS := $(MODULE_BASE_FLAGS) -gmodules
 MANDATORY_CXXMODULE_BUILD_CFLAGS := $(MODULE_BASE_FLAGS) -fcxx-modules -glldb
 
 ifeq "$(OS)" "Darwin"
-	MANDATORY_MODULE_BUILD_CFLAGS += -fcxx-modules
+	MANDATORY_MODULE_BUILD_CFLAGS += -fcxx-modules -fmodules-local-submodule-visibility
+	MANDATORY_CXXMODULE_BUILD_CFLAGS += -fmodules-local-submodule-visibility
 endif
 
 ifeq "$(MAKE_GMODULES)" "YES"