Use symlinks for .so files

[C0rn3j]

It seems all .so files are hard files instead of symlinks to one file, I had to symlink them myself:

ln -s "libkissfft-${_data_type}.so.131" "${pkgdir}/usr/lib/libkissfft-${_data_type}.so"
ln -s "libkissfft-${_data_type}.so.131.0" "${pkgdir}/usr/lib/libkissfft-${_data_type}.so.131"
install -Dm644 "libkissfft-${_data_type}.so.131.1.0" "${pkgdir}/usr/lib/libkissfft-${_data_type}.so.131.1.0"

Unsure if this should be fixed here too?