babl upstream switched from autotools to meson, therefore
all libtool files (*.la) are gone.
Every port that lists the old babl libbabl-0.1.la file in its
own libtool file has to be rebuild if other ports depends at
build time on it, here mainly opt/gegl and opt/gimp.
To find the broken files the following script kan be uses:
for f in $(grep -lrs libbabl-0.1.la /usr/lib); do
pkginfo -o $f | awk '!/^Package/ {print $1}';
done | sort -u