egl/utils: Prepare egl_util_run to be called from piglit subtests.

For future EGL tests, I want to be able to use Chad's new piglit EGL
subtest infrastructure, and use the EGL utilities convenience functions
to set up a window, surface, and context.

Currently, egl_util_run calls piglit_report_result() after calling
test.draw.  This means no other subtests get run.  Add a new field in
egl_test to specify whether piglit_report_result() should be called, and
another field to store the result returned from test.draw.

Make sure that egl_util_run() tears down the window, surface, and
context.  Previously it was relying on cleanup being done when the
process died, which won't work if we want to run a second subtest in the
same thread.

TODO:

There's still some work that could be done here to ensure the
initialization steps in egl_util_run aren't done twice (e.g. calling
XOpenDisplay, eglInitialize, etc.)  However, the tests pass in their
current state, so there's no reason they shouldn't be merged.

Thanks a bunch to Chad Versace and Rob Bradford, who helped me debug
this code!

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Chad Versace <chad.versace@linux.intel.com>
Cc: Rob Bradford <rob@linux.intel.com>
EGL_CHROMIUM_get_sync_values: Add initial test.

Test the EGL_CHROMIUM_get_sync_values extension, which is equivalent to
the glXGetSyncValuesOML function in the GLX OML_sync_control extension:

http://www.opengl.org/registry/specs/OML/glx_sync_control.txt

It's difficult to test the Media Stream Counter (MSC) without the
equivalent function to get the MSC rate (glXGetMscRateOML).  The test at
least makes sure MSC and SBC increment after two SwapBuffers() calls.
UST is system-dependent, so it may behave differently on Windows, Linux,
and Apple.  The test just makes sure it increments monotonically.

The test uses Chad's new subtest infrastructure and the EGL convenience
functions from egl-util.c.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Chad Versace <chad.versace@linux.intel.com>
Cc: Rob Bradford <rob@linux.intel.com>