cstdint is a C++11 header, LLVM provides its own version of it.

Some versions of libstdc++ forbid using cstdint in C++98 mode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201812 91177308-0d34-0410-b5e6-96231b3b80d8