工作中，xcode工程遇到一个bug
file was built for archive which is not the architecture being linked armv7
找了一些资料，发现这个lipo可以查看.a库的架构类型
lipo -info *.a看一下是不是编译为armv7的。
lipo -info libavcodec.a
Non-fat file: input/libavcodec.a is architecture: armv7
