[analyzer] Don't repeat a bug equivalence class if every report is invalid.

I removed this check in the recursion->iteration commit, but forgot that
generatePathDiagnostic may be called multiple times if there are multiple
PathDiagnosticConsumers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177214 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed