Adds glmark2 (#4469)

Now that we have acceleration, add glmark2 for benchmarking.

packages/glmark2.rb

+# Adapted from Arch Linux glmark2 PKGBUILD at:
+# https://aur.archlinux.org/cgit/aur.git/plain/PKGBUILD?h=glmark2
+
+require 'package'
+
+class Glmark2 < Package
+  description 'OpenGL ES 2.0 benchmark'
+  version '2020.04'
+  compatibility 'all'
+  source_url 'https://github.com/glmark2/glmark2/archive/2020.04.tar.gz'
+  source_sha256 '0fa7723111c928a73c04d4fa4adfc15a9dea6d335fe189f59c74ae5af26f99a2'
+
+  depends_on 'libjpeg_turbo'
+  depends_on 'libpng'
+  depends_on 'libx11'
+  depends_on 'libxcb'
+
+
+  def self.build
+      system "python2 ./waf configure --prefix=#{CREW_PREFIX} --libdir=#{CREW_LIB_PREFIX} --with-flavors x11-gl,x11-glesv2"
+      system "python2 ./waf"
+  end
+  
+  def self.install
+      system "python2 ./waf install --destdir=#{CREW_DEST_DIR}/"
+  end
+end