graphics/gegl: sort out Makefile and pet portclippy

Also:

• remove unnecessary dependency from fribidi;
• LIBRSVG2, PANGO and POPPLER used only if CAIRO is ON;
• resurect option UMFPACK;
• remove patch for powerpc* with altivec.

PR: 279280
Tested by: pkubaj (build on powerpc*)
Approved by: fluffy (gnome, maintainer)