perl: fix build failure if building dir has the "blib" string
If build dir includes the string "blib", filter it out from @INC may empty
the @INC and cause build errors like:
Can't locate ExtUtils/MakeMaker.pm in @INC \
(you may need to install the ExtUtils::MakeMaker module) \
(@INC contains: .) at Makefile.PL
Signed-off-by: Roy Li <rongqing.li@windriver.com> Signed-off-by: Wenzong Fan <wenzong.fan@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
