Starting using murmur2 when combining multiple size_t's into a single hash, and also for basic_string.  Also made hash<thread::id> ever so slighly more portable.  I had to tweak one test which is questionable (definitely not portable) anyway.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@145795 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed