Bail if context creation fails in FuzzDDLThreadingGL

Bug: oss-fuzz:31634
Change-Id: I9717d04d391c584f28d415fa728c7296edb91723
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/379038
Auto-Submit: Adlai Holler <adlai@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Adlai Holler <adlai@google.com>
1 file changed