fixes to more reliably build libyaml

- build from a tar that already has a working configure
- use Alien::Base 0.005 %c to get --with-pic
- use Alien::Base 0.005 alien_isolate_dynamic so that XS modules can link against static libs
- patch the .pc file so that an appropriate -I flag is provided
Merge pull request #3 from plicease/ab0005

fixes to more reliably build libyaml