Created by: NHZlX

when the user run the ./lite/tools/build.sh twice, there is the bug.

make[3]: *** No rule to make target 'protoc', needed by 'lite/core/framework.pb.cc'.  Stop.
CMakeFiles/Makefile2:7258: recipe for target 'lite/core/CMakeFiles/framework_proto.dir/all' failed
make[2]: *** [lite/core/CMakeFiles/framework_proto.dir/all] Error 2
make[2]: *** Waiting for unfinished jobs....