Added "DOUT" macro. This is used as a replacement for the std::cerr

stream. It centralizes the use of std::cerr so that static c'tor/d'tors
aren't scattered around all over the place. The way to use it is like this:

       DOUT << "This is a status line: " << Var << "\n";

If "-debug" is specified, it will print. Otherwise, it'll not print. If
NDEBUG is defined, the DOUT does nothing.

llvm-svn: 31798