git-rebase: support --whitespace=<option>

Pass --whitespace=<option> to git-apply.  Since git-apply and git-am
expect this, I'm always surprised when I try to give it to git-rebase
and it doesn't work.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 61b1810..0858fa8 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -8,8 +8,9 @@
 SYNOPSIS
 --------
 [verse]
-'git-rebase' [-i | --interactive] [-v | --verbose] [-m | --merge] [-C<n>]
-	[-p | --preserve-merges] [--onto <newbase>] <upstream> [<branch>]
+'git-rebase' [-i | --interactive] [-v | --verbose] [-m | --merge]
+	[-C<n>] [ --whitespace=<option>] [-p | --preserve-merges]
+	[--onto <newbase>] <upstream> [<branch>]
 'git-rebase' --continue | --skip | --abort
 
 DESCRIPTION
@@ -209,6 +210,10 @@
 	context exist they all must match.  By default no context is
 	ever ignored.
 
+--whitespace=<nowarn|warn|error|error-all|strip>::
+	This flag is passed to the `git-apply` program
+	(see gitlink:git-apply[1]) that applies the patch.
+
 -i, \--interactive::
 	Make a list of the commits which are about to be rebased.  Let the
 	user edit that list before rebasing.  This mode can also be used to