backport.pl: add a feature to the interactive mode.
backport.pl: add a feature to the interactive mode.

* tools/dist/backport.pl
  (prompt): Add an optional argument that changes the return value's semantics.
  (handle_entry): Add a 'diff' command.
    This meant adding a loop, since plain 'goto' panicked.

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1482408 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion