[PATCH] Added basic testing support for llvm-cov.

[Justin Bogner]

Yuchen Wu <yuchenericwu at hotmail.com> writes:
> Updated patch to avoid creating temporaries when testing
> llvm-cov. Added new command-line option into llvm-cov that allows for
> specifying the input file directory.

Probably best to split this into two - one patch to add the command line
option and another that adds the test. It'd also probably be cleaner to
make the command line option more like make's "-C", where it just
changes the working directory before doing anything. This would avoid
the relative vs. absolute path logic.

It'd also be nice to mention somewhere where the reference output you're
comparing against came from (gcov version, for example).