Remove context from linking state.
Remove context from linking state.

This Context could already be deleted from another thread. Better to
use save/load with the current thread.

Bug: angleproject:2464
Change-Id: Id7879a53bdfb7d1c86b09bb3e779a87afdefa873
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1756086
Reviewed-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>
Reviewed-by: Tobin Ehlis <c15ba1c6ec8841cd136fafb26b333b1f76c86fb4@google.com>
Commit-Queue: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle