Fix directive parsing in VerifyDiagnosticConsumer so that it ensures that...

Fix directive parsing in VerifyDiagnosticConsumer so that it ensures that "expected" is at the start of the word and will no longer accept typos such as "junkexpected-*" as a valid "expected-*" directive.  A very few test-cases had to be amended to adhere to the new rule.

Patch reviewed by David Blaikie.

llvm-svn: 166279