revert HTile lifetime changes and opt-in ZMask support

src/common/emulatorConfig.cpp

@@ -189,10 +189,6 @@ bool SyncRawImageBuffersEnabled() {
 	return g_config->sync_raw_image_buffers;
 }
 
-bool SupportZmaskEnabled() {
-	return g_config->support_zmask;
-}
-
 bool TessellationEnabled() {
 	return g_config->tessellation_enabled;
 }