Simplify build process so external libcld is not required.

Instead of libcld just link the .o files from cld-src into the perl XSLoaded module directly

This makes it much easier to use when perl lives in non-standard location (i.e. local::lib or similar)
Merge pull request #3 from ashb/simplify_build

Can't easily use in non-standard perl location (local::lib etc.)