Previously these tests didn't initialize GLEW, presumably because they
only use (a) GL 1.0 functions, which bypass GLEW, and (b) GLX
functions, which they bind to using glXGetProcAddressARB().  Once we
switch to using piglit-dispatch instead of GLEW, we will need to
initialize it in order for the GL 1.0 functions to work.  This patch
adds a call to glewInit() in the place where a call to
piglit_dispatch_default_init() will eventually be needed.

Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>