Merge bmake-20230622

Merge commit '3e39ce563b9ba25883e5aa37d9799eda9e57c1e0'

Merge bmake-20201117

o allow env var MAKE_OBJDIR_CHECK_WRITABLE=no to skip writable
checks in InitObjdir. Explicit .OBJDIR target always allows
read-only directory.

o More code cleanup and refactoring.

o More unit tests

MFC after: 1 week

Update to bmake-20201101

Lots of new unit-tests increase code coverage.

Lots of refactoring, cleanup and simlpification to reduce
code size.

Fixes for Bug 223564 and 245807

Updates to dirdeps.mk and meta2deps.py