Exit with error when running libavtest and not configured with --enable-gpl.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@9141 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

tests/Makefile

@@ -36,6 +36,7 @@ libavtest:
 	@echo
 	@echo "This test requires FFmpeg to be compiled with --enable-gpl."
 	@echo
+	@exit 1
 endif
 
 ifeq ($(CONFIG_SWSCALER),yes)