tests/docker: Update VirGL to v0.8.0

tests/docker: Update VirGL to v0.8.0

Building the qemu:debian-amd64 fails when building VirGL:

  make[2]: Entering directory '/usr/src/virglrenderer/src/gallium/auxiliary'
    CC       cso_cache/cso_cache.lo
    CC       cso_cache/cso_hash.lo
    CC       os/os_misc.lo
    CC       util/u_debug.lo
    CC       util/u_debug_describe.lo
    CC       util/u_format.lo
    GEN      util/u_format_table.c
  Traceback (most recent call last):
    File "./util/u_format_table.py", line 168, in <module>
      main()
    File "./util/u_format_table.py", line 164, in main
      write_format_table(formats)
    File "./util/u_format_table.py", line 132, in write_format_table
      print("   %s,\t/* is_array */" % (bool_map(format.is_array()),))
    File "/usr/src/virglrenderer/src/gallium/auxiliary/util/u_format_parse.py", line 164, in is_array
      return self.array_element() != None
    File "/usr/src/virglrenderer/src/gallium/auxiliary/util/u_format_parse.py", line 73, in __eq__
      return self.type == other.type and self.norm == other.norm and self.pure == other.pure and self.size == other.size
  AttributeError: 'NoneType' object has no attribute 'type'
  make[2]: Leaving directory '/usr/src/virglrenderer/src/gallium/auxiliary'
  make[2]: *** [Makefile:906: util/u_format_table.c] Error 1
  make[1]: *** [Makefile:631: install-recursive] Error 1

VirGL commits a8962eda1..a613dcc82 fix this problem.
Update to VirGL 0.8.0 which contains them.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200212202709.12665-4-philmd@redhat.com>
Message-Id: <20200316172155.971-5-alex.bennee@linaro.org>