git-merge-recursive: honor merge.conflictstyle once again

This was originally implemented in c236bcd061
but was lost to a mismerge in 9ba929ed65.

Signed-off-by: Matt McCutchen <matt@mattmccutchen.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

merge-recursive.c

@@ -1332,7 +1332,7 @@ static int merge_recursive_config(const char *var, const char *value, void *cb)
 		o->merge_rename_limit = git_config_int(var, value);
 		return 0;
 	}
-	return git_default_config(var, value, cb);
+	return git_xmerge_config(var, value, cb);
 }
 
 void init_merge_options(struct merge_options *o)