[Piglit] RFC add KHR_no_error profile

[Timothy Arceri]

This series adds a new profile for testing KHR_no_error, initially
all tests besides shader_runner tests will be skipped.

To enable the tests config.khr_no_error_support will need to be
set for each test, this will be a bunch of work and will
probably require some tests split out error checking into a
separate test to enable testing of non-error paths.

Also missing is the piglit support for enabling the
no error flag as I'm still waiting for the GLX spec to be
released. For now it is intended to be used with the
MESA_NO_ERROR env var.

Adding config.khr_no_error_support to the c file seemed much
cleaner and less error prone to me over adding an extra param
to the python profile.

Any feedback on this approach is appreciated.