o ignore '.POSIX:' if not in first non-comment line
of Makefile as specified by POSIX.
add unit-tests for above.
Merge commit '92bfae0e6bd53a7a0d6fe55e70a916d86cf26e8b'
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