prefix=/Workspace/Support/ijkplayer-ios/ios/build/ffmpeg-armv7/output  xcrun -sdk iphoneos clang
xcrun -sdk iphoneos clang is unable to create an executable file.
C compiler test failed.

If you think configure made a mistake, make sure you are using the latest
version from Git.  If the latest version fails, report the problem to the
ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.freenode.net.
Include the log file "ffbuild/config.log" produced by configure as this will help
solve the problem.

解决方案是

//报错的原因是因为脚本找不到xcode了
sudo /usr/bin/xcode-select -switch /Applications/Xcode.app/Contents/Developer