raw_ostream.cpp: Introduce <fcntl.h> to let O_BINARY provided. Or, llvm::outs() would be set to O_TEXT by default.

llvm/test/Object/check_binary_output.ll is expected to pass on win32.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186480 91177308-0d34-0410-b5e6-96231b3b80d8