Relevant/interesting changes:
o parse.c: fix out-of-bounds read when parsing an invalid line
https://bugs.freebsd.org/265119
fix memory leak in wildcard targets and sources
fix off-by-one error in buffer for .WAIT nodes
o allow to randomize build order of targets
.MAKE.MODE += randomize-targets can help uncover dependency bugs
Lots of code refactoring, simplification and cleanup.
Lots of new unit-tests providing much higher code coverage.
All courtesy of rillig at netbsd.
Other significant changes:
o new read-only variable .SHELL which provides the path of the shell
used to run scripts (as defined by the .SHELL target).
o new debug option -dl: LINT mode, does the equivalent of := for all
variable assignments so that file and line number are reported for
variable parse errors.