graphics/katarakt: prepare for poppler 20.08.0 (fixed)

• unfortunately the fix applied in r544366 broke the build in the current tree (and I impatiently committed before the trunk testbuild was finished)
• simply remove all the broken POPPLER_VERSION checks, the version in ports is well-defined and years newer than anything that is checked against.

PR: 248419
Pointy hat: tcberner