Changes: exit from pixelchanged when given unrecognized commandline option

RevBy: TrustMe

Details: This caused some headaches in performance testing, when the
pixelchanged binary got some bogus commandline argument. It's better
to just fail and exit the program than to wait indefinitely.

tests/Common/TestApps/pixelchanged/main.c

@@ -214,6 +214,7 @@ int main(int argc, char **argv)
             quit_when_found = 1;
         } else {
             fprintf(stderr, "Unrecognized option %s\n", argv[arg]);
+            return EXIT_FAILURE;
         }
         ++arg;
     }