diff -c/--cc: do not include uninteresting deletion before leading context
diff -c/--cc: do not include uninteresting deletion before leading context

When we include a few uninteresting lines before the interesting ones as
context, we are only interested in seeing the surviving lines themselves
and not the deleted lines that are before them.  Mark the added leading
context lines in give_context() and not show deleted lines form them.

Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git