Reapply: [llvm-rc] Add basic RC scripts parsing ability.

As for now, the parser supports a limited set of statements and
resources. This will be extended in the following patches.

Thanks to Nico Weber (thakis) for his original work in this area.

This patch was originally submitted as r311175 and got reverted
in r311177 because of the problems with compilation under gcc.

Differential Revision: https://reviews.llvm.org/D36340

llvm-svn: 311184