Fix crash in SQLite sqlite3Fts3Incrmerge

Backports https://www.sqlite.org/src/info/361eb2f682a303bb
and https://sqlite.org/src/info/67da31e24ebb49c4

Bug:  998494
Change-Id: Icd11546d8f504a1c6df7bc5692b917ded35ba486
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1835704
Reviewed-by: Darwin Huang <huangdarwin@chromium.org>
Commit-Queue: Darwin Huang <huangdarwin@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#704392}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: f9f8801edc66cb0deed4c9cdd238e4856dec5c02
12 files changed