Add lib64 path search on Linux (#88)
Add lib64 path search on Linux (#88)

The libclang.so is located at `/usr/lib64/llvm/7/lib64/libclang.so` on my Gentoo linux, where`/usr/lib64/llvm/7/` can be obtained by `llvm-config --prefix`. It would be better to also search `lib64` subdirectory, as `lib` subdirectory does not exist on my system.
KyleMayes/clang-sys,KyleMayes/clang-sys