[Piglit] OML_sync_control tests

[Jamey Sharp]

These patches are our attempts to validate that glX OML_sync_control
implementations sync to vblank, and otherwise conform to the extension's
specification. The existing tests don't demonstrate a variety of
implementation bugs that we've observed in current drivers, so this is
our attempt to demonstrate those bugs.

Patch 1 fixes argument setup for the existing OML_sync_control tests,
which causes the swapbuffersmsc-return test to pass where it failed
before. (Together with xserver patches that are now in git master, the
existing tests all pass for me after this patch is applied.)

Patches 2-6 are framework improvements to simplify both existing tests
and the newly added ones.

Patches 7 and 9 add our new tests, and patch 8 adds timeouts to make it
easier to run the test suite on the, let's say, non-conformant driver
implementation on Theo's laptop.

I sent patches 1-3 to the list last week for review but haven't seen any
responses yet.

Jamey and Theo