abort() in dbgutil mode if OpenGL shader compilation fails

Otherwise it's quite annoying to miss e.g. a typo in the shader code
if the code falls back to another way of handling the operation.

Change-Id: I585be85f739929f0f422dc031a36dc83077f6820
Reviewed-on: https://gerrit.libreoffice.org/70771
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

vcl/source/opengl/OpenGLHelper.cxx

@@ -135,6 +135,10 @@ namespace {
         }
         else
             SAL_WARN("vcl.opengl", rDetail << " shader: " << rName << " compile " << nId << " failed without error log");
+
+#ifdef DBG_UTIL
+        abort();
+#endif
         return 0;
     }
 }