Merge branch 'master', remote-tracking branch 'upstream/master'
fix Makefile in tools/performance

1. move $(LIBS) to the end of gcc parameters.
http://stackoverflow.com/questions/14623415/gcc-g-parameter-order

2.remove -Werror flag, as "paddr" at virt_addr.c:73 set but not used
restore CFLAGS "-Werror"
Merge pull request #87 from mzguanglin/fix-tool-performance

fix Makefile in tools/performance