[-Wunreachable-code] include some enum constants in "configuration value" heuristic

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203026 91177308-0d34-0410-b5e6-96231b3b80d8
[-Wunreachabe-code] add test for double 'break'.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203027 91177308-0d34-0410-b5e6-96231b3b80d8