3.99.90
Add requirement for plugin_is_GPL_compatible symbol in loaded objects.
Expand the loadable object support.
Convert all "`'" quotes to "''" per new GNU Coding Standard guidelines. Fixes Savannah bug #34530.
[SV #38051] Recover all MAKEFLAGS after makefile rebuild step is complete.
When .POSIX: is specified use POSIX-standard macro values by default.
Add a new variable: GNUMAKEFLAGS
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.