i965: Fix uint64_t overflow in intel_client_wait_sync()

i965: Fix uint64_t overflow in intel_client_wait_sync()

DRM_IOCTL_I915_GEM_WAIT takes an int64_t for the timeout value but
GL_ARB_sync takes an uint64_t.  Further, the ioctl used to wait
indefinitely when passed a negative timeout, but it's been broken and
now returns immediately in that case.  Thus, if an application passes
UINT64_MAX to wait forever, we overflow to -1LL and return immediately.
Work around this mess by clamping the wait timeout to INT64_MAX.

Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Chad Versace <chad.versace@intel.com>