place: fix finalizaiton of place channels stuck in a GC'ed channel

Lack of ordering on finalization requires some care for explicit
clean-up actions in a finalizer.

Back-port of commit a5f26013ab.
db: temporary workaround for SSL one-record-per-write issue
(cherry picked from commit ef3dff1ceca8ee3058b5276197b1918117de79de)
Fix the filename of the Ubuntu build.

The actual file *is* an x86_64 build.

(cherry picked from commit 3440e29d48ec8dff73b9768e5ebbfef4b85e4c9c)
Improve some texts.
(cherry picked from commit 90b0f262cdb94eb58711a13b727d98756f3c1d2b)
Allow multiple extra files.
(cherry picked from commit 8b7a9c6b9ea036b3350a2f6a396c5f4d0bf10094)
Delay running git, to avoid a premature warning about $GIT_DIR.

(cherry picked from commit 41c0156fe3acf5545d12ffd166c3e71a79efb0c2)
Explain how to build the pages.
(cherry picked from commit 46db1d2d64527784b5cdeb0a2caac7eed5bc67e5)
updated HISTORY

Merge to 5.3.6 release.
(cherry picked from commit b23d8ed2b476c4577c8651fa662f89bf32fb857b)
Oops don't mention file reorg in stepper HISTORY.txt

Please merge to 5.3.6 release
(cherry picked from commit beae23fea22bc7fe2f010c751161237354a8be49)