Merge branch 'jc/diff-s-with-other-options'

The "-s" (silent, squelch) option of the "diff" family of commands
did not interact with other options that specify the output format
well.  This has been cleaned up so that it will clear all the
formatting options given before.

* jc/diff-s-with-other-options:
  diff: fix interaction between the "-s" option and other options

diff --cc Documentation/diff-options.txt
Simple merge

diff --cc diff.c
Simple merge