4.3.91
Add preprocessor macros for different platforms
Always restore global environ if we use vfork
tests: Allow run_make_test() to avoid passing -f
[SV 56301] Fail if an included makefile can't be built
* tests/scripts/targets/WAIT: [SV 63071] Remove possible test races.
Fix tests for MacOS and Windows
Refresh the test suite framework implementation.
Update the test template. A few fixes in run_make_test(). Rename implicit_prereq_eval to patternrules, to be the start of a suite of tests of pattern rules.