Set Diag.ErrorOccurred even if a DiagnosticConsumer does not want it in

diagnostic count.

If a DiagnosticConsumer sub-class overwrites IncludeInDiagnosticCounts,
this should change diagnostic counts. However, it currently also
influences Diag.ErrorOccurred, which in turn influences the behavior of
parsing and semantic analysis (in a way that can make it crash).

llvm-svn: 164824