i965: fix segfault on low memory conditions

i965: fix segfault on low memory conditions

When out of memory (in at least one case, triggered by a longrunning
memory leak), this code will segfault and crash.  By checking for the
out-of-memory condition, the system can continue, and will report
the out-of-memory error later, a much preferable outcome.
(cherry picked from commit 44a4abfd4f8695809eaec07df8eeb191d6e017d7)