This fixes an error in do_patch when using "PATCHTOOL = "patch""
error message:
checking file gcc/configure.ac Hunk #1 FAILED at 6602.
(From OE-Core rev: f75a1eddc7c01d9a83d0a1114fc0d6aaa79d8806)
Signed-off-by: Wang Mingyu <wangmy@cn.fujitsu.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>