javascriptcoregtk.recipe: Fix png.h check
javascriptcoregtk.recipe: Fix png.h check

This was failing on OS X because the compiler wasn't implicitly checking
the current directory too

ford-prefect/cerbero,ramaxlo/cerbero,superdump/cerbero,ford-prefect/cerbero,EricssonResearch/cerbero,EricssonResearch/cerbero,AlertMe/cerbero,AlertMe/cerbero,sdroege/cerbero,sdroege/cerbero,shoreflyer/cerbero,multipath-rtp/cerbero,ramaxlo/cerbero,shoreflyer/cerbero,ford-prefect/cerbero,sdroege/cerbero,AlertMe/cerbero,multipath-rtp/cerbero,AlertMe/cerbero,ikonst/cerbero,ikonst/cerbero,superdump/cerbero,EricssonResearch/cerbero,multipath-rtp/cerbero,ramaxlo/cerbero,ikonst/cerbero,multipath-rtp/cerbero,EricssonResearch/cerbero,superdump/cerbero,ikonst/cerbero,shoreflyer/cerbero,shoreflyer/cerbero,ramaxlo/cerbero,ford-prefect/cerbero,sdroege/cerbero,sdroege/cerbero,AlertMe/cerbero,multipath-rtp/cerbero,ramaxlo/cerbero,superdump/cerbero,EricssonResearch/cerbero,ikonst/cerbero,shoreflyer/cerbero