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.

LLVM D Compiler (LDC)

This compiler is based on the Digital Mars D (DMD) compiler frontend, and
the LLVM compiler toolkit. See LICENSE for licensing information.

For more information, including build instructions, visit the LDC website:

http://www.dsource.org/projects/ldc