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: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-rebase.txt

@@ -8,8 +8,9 @@ git-rebase - Forward-port local commits to the updated upstream head
 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 @@ OPTIONS
 	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

git-rebase.sh

@@ -216,8 +216,11 @@ do
 	-v|--verbose)
 		verbose=t
 		;;
+	--whitespace=*)
+		git_am_opt="$git_am_opt $1"
+		;;
 	-C*)
-		git_am_opt=$1
+		git_am_opt="$git_am_opt $1"
 		shift
 		;;
 	-*)