Are you using 10.1?
If so, goodluck enabling pdflib support. Apple explicitely says they havent got it to work

the people at pdflib are just starting to realize that there are problems with 10.1

and ive tried about every install routine possible and still no luck.
after gettings through my share of namespace errors and finding fixes for those, pdflib complies and installs just fine, then i rebuild php with --with-pdflib=<pdflib-install-dir> and it configures fine. php then installs without an error, but still wont find the pdflib functions. im sure im close to getting it to work, but im ready to put my fist through the preverbial wall.