The whole multi-threading changes in the help plug-in seem to badly
break on macOS. See discussion in reopened#12898.
We decided to get rid of it for now and see later if we need to
reimplement this (after understanding what is going on).
Revert "plug-ins: fix#13049 Calling help on unknown help-id causes..."
This reverts commit 7d153bcc6d.
Revert "plug-ins/help: fix thread unnecessarily waiting when locale_parse failed"
This reverts commit fd0ccfa16c.
Revert "plug-ins/help: fix crash when locale is NULL"
This reverts commit 4075add5b4.
Revert "plug-ins: fix failing to access help from within GIMP"
This reverts commit 38f0527ebc.
Revert "plug-ins: add some better error handling when the docs XML request/parsing fails."
This reverts commit 543bb374a8.
Revert "plug-ins: try to load the gimp-help.xml file in a thread."
This reverts commit f2d47e910b.
8c077d50d1