Add VerifyDiagnosticsClient, to replace old -verify.
 - This reimplements -verify as just another DiagnosticClient, which buffers the diagnostics and checks them when the source file is complete. There are some hacks to make this work, but they are all internal, and this exposes a better external interface.

 - This also tweaks a few things:
   o Errors are now just regular diagnostics.
   o Frontend diagnostics are now caught (for example, errors in command line arguments), although there isn't yet a way to specify that they are expected. That would be nice though.

 - Not yet used.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@88748 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed