Handle empty clang output when there is a gcc-clang diff.

Author: fpapadopou

Symfony/src/Codebender/CompilerBundle/Handler/CompilerHandler.php

@@ -713,6 +713,8 @@ private function doCompile($compiler_config, &$files, $dir, $CC, $CFLAGS, $CPP,
                         }
 
                         $resp["message"] = $this->pathRemover ($output, $compiler_config);
+                        if ($resp["message"] == "")
+                            $resp["message"] = $this->pathRemover($avr_output, $compiler_config);
                         return $resp;
                     }
                     unset($output);