bash: support 'git am's new '--continue' option

Signed-off-by: NSZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -667,7 +667,7 @@ _git_am ()
 {
 	local cur="${COMP_WORDS[COMP_CWORD]}" dir="$(__gitdir)"
 	if [ -d "$dir"/rebase-apply ]; then
-		__gitcomp "--skip --resolved --abort"
+		__gitcomp "--skip --continue --resolved --abort"
 		return
 	fi
 	case "$cur" in