llvm-cov: Added -c option for branch counts.

This will cause llvm-cov to output branch counts instead of branch
probabilities. -b must be enabled.

Also updated tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197594 91177308-0d34-0410-b5e6-96231b3b80d8