Fix linking against pthread/rt
$ shasum -a 256 llvm-obfuscator-arm-x86.txz
470d5d75b437e5afd94f2fb5744fb8be7546a7ac3cb041de7d2f619988fa1f80 llvm-obfuscator-arm-x86.txz
$ shasum -a 256 llvm-obfuscator-arm-x86.txz
470d5d75b437e5afd94f2fb5744fb8be7546a7ac3cb041de7d2f619988fa1f80 llvm-obfuscator-arm-x86.txz