Add #include raw_ostream.h in lib/Target/R600/SIFixSGPRCopies.cpp

This was casuing my release+asserts build on Windows to fail.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194747 91177308-0d34-0410-b5e6-96231b3b80d8