Bump DiagnosticDriverKinds count; we're close to hitting it.

 $ grep '= DIAG_START_DRIVER' include/clang/Basic/DiagnosticIDs.h
       DIAG_START_FRONTEND      = DIAG_START_DRIVER          +  100,
 $ grep 'def ' include/clang/Basic/DiagnosticDriverKinds.td | wc -l
       98

llvm-svn: 256956