Clean up the job pipe handling.

Clean up the job pipe handling.

scheduler/job.c:
    - cupsdStartJob(): Add abort_job label with job abort code
      and use goto for common job abort logic; also close all
      status pipes.

scheduler/main.c:
    - cupsdOpenPipe(): Reset file descriptors to -1 on error.

git-svn-id: svn+ssh://src.apple.com/svn/cups/cups.org/trunk@5299 7a7537e8-13f0-0310-91df-b6672ffda945