opencl: bail out early in missing OpenCL case.

Change-Id: I2ff1466ec89f4ad9743cedbfa5dd52be8bf86590
Reviewed-on: https://gerrit.libreoffice.org/27136Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>

desktop/source/app/opencl.cxx

@@ -122,6 +122,7 @@ void Desktop::CheckOpenCLCompute(const Reference< XDesktop2 > &xDesktop)
     {
         SAL_WARN("opencl", "Failed to initialize OpenCL for test");
         OpenCLZone::hardDisable();
+        return;
     }
 
     // Append our app version as well.