Update mesa to version 20.0.8 (bug #58689). * src/mesa.mk: Update version and checksum. Add build-meson to dependecies. Update build rule to use meson and ninja as the build tools. * src/mesa-1-meson.patch: Add new patch. * src/mesa-1-fixes.patch: Remove old patch for the scons rule that is no longer needed. * dist-files.mk: Update file list. * src/build-mako.mk: Depend on and use python3. * src/build-markupsafe.mk: Depend on and use python3.

#!/bin/bash
## bootstrap script
## Run this to generate the configure script

set -e      # halt if unhandled error
aclocal
autoconf    # generate configure script