Mac系统pycrypto安装失败command 'gc

fatal error: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo: can't figure out the architecture type of: /var/tmp//ccW9pG1V.out
    error: command 'gcc-4.2' failed with exit status 1
    
    ----------------------------------------
Command "/Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python -u -c "import setuptools, tokenize;__file__='/private/tmp/pip-build-7PDrqz/pycrypto/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-mJXyAh-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/tmp/pip-build-7PDrqz/pycrypto/

结局方法：执行下xcode-select --install命令，然后重新安装。