This is a Buildroot package for the (old) "s3" X driver that is no longer available in Buildroot's official packages.
The source was pulled directly from http://xorg.freedesktop.org/releases/individual/driver/xf86-video-s3-0.7.0.tar.bz2
This driver does not support render acceleration as it only supports XAA, which modern releases of XOrg haven't supported since 1.13 (~2012) or so.