This patch tidies up the llvm-strings testing by:
1. Adding comments to every test.
2. Getting rid of canned input files, and having the tests generate
them on the fly (this makes the tests self-contained).
3. Adding missing test coverage.
4. Renaming some tests that weren't clear as to their purpose.
5. Adding extra checking of various cases, formatting etc.
6. Removing a test that didn't seem to have any useful purpose for
testing llvm-strings.
Reviewed by: rupprecht, grimar, MaskRay
Differential Revision: https://reviews.llvm.org/D66015
llvm-svn: 368555
