Diagnose misordered initializers in constructor templates immediately instead of

Diagnose misordered initializers in constructor templates immediately instead of
when they're instantiated.  Merge the note into the -Wreorder warning;  it
doesn't really contribute much, and it was splitting a thought across diagnostics
anyway.  Don't crash in the parser when a constructor's initializers end in a
comma and there's no body;  the recovery here is still terrible, but anything's
better than a crash.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@100922 91177308-0d34-0410-b5e6-96231b3b80d8