[Ohrrpgce] SVN: teeemcee/13446 scons: fix a transpiledir= race condition

[subversion at HamsterRepublic.com]

teeemcee
2023-12-29 14:00:58 -0800 (Fri, 29 Dec 2023)
346
scons: fix a transpiledir= race condition

It seems scons runs Actions in parallel so sometimes a file Copy was run
before the destination directory's Mkdir.

Half-rewrote ohrbuild.copy_source_actions yet again to use a custom Action, but
in future it can be deleted if we make SCons 4.5.0 a requirement.

This also reduces the file copying spam.
---
U   wip/SConscript
U   wip/ohrbuild.py