Test for unsigned RS setters.

BUG=6764163

This verifies that we don't trample memory with our unsigned set_*()
operations. Previous versions of llvm-rs-cc generated code that could
accidentally overwrite neighboring locations (due to setVar() being
called on the larger Dalvik types for unsigned globals).

Change-Id: I014496122a05cf425efa160978d0738a5233742e