Why isn't mesa compiled with GLES ?
 

Looking at the SlackBuild:

./configure \
$SLKARCHCONFARGS \
--enable-shared-glapi \
--with-gallium-drivers="$SLKARCHGALLIUMDRIVERS" \
--enable-osmesa \
--enable-xa \
--prefix=/usr \
--sysconfdir=/etc \
--libdir=/usr/lib${LIBDIRSUFFIX} \
--mandir=/usr/man \
--docdir=/usr/doc/mesa-$VERSION \
--build=$ARCH-slackware-linux-gnueabi \


But mesa sources ./configure --help reports:

--enable-gles1 enable support for OpenGL ES 1.x API [default=no]
--enable-gles2 enable support for OpenGL ES 2.x API [default=no]

My bad, I didn't read enough:

export SLKARCHCONFARGS="--enable-gles1 --enable-gles2 --enable-openvg --enable-gallium-egl" ;;