While fixing up some incorrect STAGING_DIR_HOSTPKG uses I introduced, I noticed that the LIBPNG12_CONFIG variable is not used by libgd anymore (it is called LIBPNG_CONFIG now). As the build runs fine without setting LIBPNG_CONFIG, let's just remove the unused line. Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>lilik-openwrt-22.03