Updating the capability attribute diagnostics to be more capability-neutral. Instead...

Updating the capability attribute diagnostics to be more capability-neutral. Instead of using terminology such as "lock", "unlock" and "locked", the new terminology is "acquire", "release" and "held". Additionally, the capability attribute's name argument is now reported as part of the diagnostic, instead of hard coding as "mutex."

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@205359 91177308-0d34-0410-b5e6-96231b3b80d8