Zap another dead 'break' statement.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203282 91177308-0d34-0410-b5e6-96231b3b80d8
[-Wunreachable-code] Treat constant globals as configuration values in unreachable code heuristics.

This one could possibly be refined even further; e.g. looking
at the initializer and see if it is truly a configuration value.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203283 91177308-0d34-0410-b5e6-96231b3b80d8