Update llvm-base-types to be compatible with LLVM 3.3.

The first significant change in this pull request is that the llvm::DICompileUnit/MetaDWCompileUnit's isMain field was removed in http://llvm.org/viewvc/llvm-project?view=revision&revision=176910.

The second is that LLVM 3.3 removed DIType::getFile, replacing it with a filename/directory pair; I've updated the corresponding types on the Haskell end.

There are still some issues remaining, namely the Attributes change from LLVM 3.2 to 3.3. However, function attributes aren't fully implemented in llvm-data-interop anyway, so I'm not worrying about them for now.

This pull request corresponds with https://github.com/travitch/llvm-data-interop/pull/4.