Remove redundant source, object files.

[jonathan]

Summary

There are a few instances in which a source or object file is described
twice in a build. This doesn't cause a problem when linking ELF objects
together, but it causes llvm-link to fail when building things via
bitcode instead of the traditional compilation path. Even when building
with ELF objects, however, it's still poor hygene to have these kinds of
redundancies.

[jonathan]

Add reviewers who have touched these makefiles recently