pip 错误unused-command-line-argument-hard-error-in-future解决办法
在我的MacAir上，用pip安装一些Python库时，偶尔就会遇到一些报错，关于“unused-command-line-argument-hard-error-in-future”，错误如下：
cc-fno-strict-aliasing-fno-common-dynamic-archx86_64-archi386-g-Os-pipe-fno-common-fno-strict-aliasing-fwrapv-mno-fused-madd-DENABLE_DTRACE-DMACOSX-DNDEBUG-Wall-Wstrict-prototypes-Wshorten-64-to-32-DNDEBUG-g-fwrapv-Os-Wall-Wstrict-prototypes-DENABLE_DTRACE-archx86_64-archi386-pipe-I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7-cpsutil/_psutil_osx.c-obuild/temp.macosx-10.9-intel-2.7/psutil/_psutil_osx.o
clang:error:unknownargument:'-mno-fused-madd'[-Wunused-command-line-argument-hard-error-in-future]
clang:note:thiswillbeaharderror(cannotbedowngradedtoawarning)inthefuture
error:command'cc'failedwithexitstatus1