Now the two possible uses of not are
* not cmd
Will return true if cmd doesn't crash and returns false.
* not --crash cmd
Will return true if cmd crashes.
It will be used/tested in a followup commit for the clang crash recovery
testing.
llvm-svn: 185678
It was only used to implement ExecuteAndWait and ExecuteNoWait. Expose just
those two functions and make Execute and Wait implementations details.
llvm-svn: 183864