Add an llvm::OStream workalike class for use with Logger::cout(), with the

crucial difference being special handling of `llvm::Type`s so they get printed
by name rather than printing their full representation (which can be positively
*huge*).

This allows re-enabling some logger calls that were disabled due to extreme
verbosity.

gen/toobj.cpp

@@ -385,7 +385,7 @@ void assemble(const llvm::sys::Path& asmpath, const llvm::sys::Path& objpath)
     if (Logger::enabled()) {
         Logger::println("Assembling with: ");
         std::vector<const char*>::const_iterator I = Args.begin(), E = Args.end();
-        std::ostream& logstr = *Logger::cout().stream();
+        Stream logstr = Logger::cout();
         for (; I != E; ++I)
             if (*I)
                 logstr << "'" << *I << "'" << " ";