Fix llvm-rc tests.

Summary:
Follow-up for D56743.
* Add more "--" in llvm-rc invocations.
* Add llvm-rc to the tools list. This uses full path to llvm-rc in test
  RUN lines (llvm-lit -v), making them copy-pasteable.

Reviewers: mstorsjo, zturner

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59858

llvm-svn: 357118