SATestBuild should not ask for non-existent checkers.

- "cocoa" was moved to "osx.cocoa" a long time ago.
- "cplusplus" would be a valid package except we don't have any C++ checkers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160821 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed