[PATCH] Add clang headers that fix machine-dependent definitions on FreeBSD 9.2

[Tobias M]

>Can you get the sources of the cmake version you're dealing with? Alternatively, can you try to build the original v3.0.0 sources on your machine and see if it behaves differently for copy_if_different?
So I freshly downloaded cmake 3.0 source, build it and installed it to ~/cmake3.

```
bash-3.2$ touch x
bash-3.2$ rm -rf a && ~/cmake3/bin/cmake -E copy_if_different x a/b/c/x
bash-3.2$ tree .
.
├── a
│   └── b
│       └── c
│           └── x
└── x

3 directories, 2 files
```

> what does it print for your config?
```
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/machine/_stdint.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/machine/_stdint.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/machine/_types.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/machine/_types.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/altivec.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/altivec.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/ammintrin.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/ammintrin.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/arm_acle.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/arm_acle.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/avxintrin.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/avxintrin.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/avx2intrin.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/avx2intrin.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/bmiintrin.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/bmiintrin.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/bmi2intrin.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/bmi2intrin.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/emmintrin.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/emmintrin.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/f16cintrin.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/f16cintrin.h'
'/Users/tobias/dev/rep/llvm/tools/clang/lib/Headers/float.h' -> '/Users/tobias/dev/rep/llvm_build/./lib/clang/3.5.0/include/float.h'
```
Don't know if that helps. Let me know if you need further info or could you reproduce this issue?

http://reviews.llvm.org/D3908