It is helpful when exclude a lot of layers. It uses python re, and
supports multiple patterns (separated by space).
(From OE-Core rev: b5170882feb0f3bc2dddc213b6d115dfa87b7cc1)
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>