Pass all relevant CFLAGS on to external/libexttextcat

Change-Id: I05f25748dd29c80812328265ddb9f071ac4ae91a

external/libexttextcat/ExternalProject_exttextcat.mk

@@ -17,7 +17,7 @@ $(call gb_ExternalProject_get_state_target,exttextcat,build):
 	$(call gb_ExternalProject_run,build,\
 		./configure --disable-shared --with-pic \
 			$(if $(filter YES,$(CROSS_COMPILING)),--build=$(BUILD_PLATFORM) --host=$(HOST_PLATFORM)) \
-		CFLAGS="$(if $(debug),-g) $(if $(filter TRUE,$(HAVE_GCC_VISIBILITY_FEATURE)),-fvisibility=hidden) \
+		CFLAGS="$(CFLAGS) $(gb_VISIBILITY_FLAGS) $(gb_DEBUG_CFLAGS) $(gb_COMPILEROPTFLAGS) \
 		$(if $(filter AIX,$(OS)),-D_LINUX_SOURCE_COMPAT)" \
 		&& $(MAKE) \
 	)