This updates tools/bash-completion.sh to consider flags defined
in src/wasm/wasm-feature-flags.h.

No-Try: true
Change-Id: I0556d237608c88a87d65f739c856f94e35e2123e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2761398
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73423}