No, I have tried the symlink, and it doesn't work. It DID however, break some other symlinks
As far as I know of, the only thing depending on this version of libpng1.2 is the gmic_gimp plug-in. It also needs libfftw, libfftw_threads. I am not in contact with GREYC's and do not know if they're working on updates to suit the newer versions of libpng.