Is there any easy way to debug (via GDB) problems with binary modules in Perl?

Sure, compile debug version of perl, debug version of imagemagick and all its prerequisites ... fireup gdb and do something gdb-ish with the expert c-knowledge of perl internals :)

panic: pp_iter

(P) The foreach iterator got called in a non-loop context frame.

If it were me, i'd report the bug upstream to all parties concerned :)