WASM: don't run gfx tests on startup

Change-Id: Ibc04b5c1bb3972544fa605447c635b4af84f7584
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/150668
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <thorsten.behrens@allotropia.de>

desktop/source/app/app.cxx

@@ -1557,12 +1557,14 @@ int Desktop::Main()
         CheckOpenCLCompute(xDesktop);
 #endif
 
+#if !defined(EMSCRIPTEN)
         //Running the VCL graphics rendering tests
         const char * pDisplay = std::getenv("DISPLAY");
         if (!pDisplay || pDisplay[0] == ':')
         {
             runGraphicsRenderTests();
         }
+#endif
 
         // Post user event to startup first application component window
         // We have to send this OpenClients message short before execute() to