- don't pass path to pdftocairo to configure

- don't pass path to pdftocairo to configure
- rel 3

When pdftocairo path is passed to configure it gets set as
default pdf to ps convert program for pdftops filter which
confuses that filter and makes it behave badly.

[Job 1322] Started filter pdftops (PID 3549)
[Job 1322] Started filter pstops (PID 3550)
[Job 1322] Error: one of the output format options (-png, -jpeg, -ps, -eps, -pdf, -svg) must be used.

http://lists.pld-linux.org/mailman/pipermail/pld-users-pl/2013-December/078150.html