more changes for new-style version numbers (versions numbers on

more changes for new-style version numbers (versions numbers on
the filesystem look like 5.5.640, except on DOS-DJGPP and VMS where
they look like 5_5_640; delete @Config{pm_apiversion,xs_apiversion};
split $Config{apiversion} into three, @Config{apirevision,apiversion,
apisubversion} for CPP friendliness; $Config{sitelib} now defaults
to .../site_perl/$version, just like $Config{privlib}, making sitelib
completely independent across versions and substantially eliminating
chances of breaking older installations by overwriting newly built
extensions; all this means compatibility inclusions for @INC will need
to take into account older sitelib versions (this still TODO)

windows, vms, dos tweaks for the above

p4raw-id: //depot/perl@4773