[Support] Move Stream library from MSF -> Support.

After several smaller patches to get most of the core improvements
finished up, this patch is a straight move and header fixup of
the source.

Differential Revision: https://reviews.llvm.org/D30266

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296810 91177308-0d34-0410-b5e6-96231b3b80d8
77 files changed