Update old-style definitions to ANSI, remove a couple of register
definitions along the way. Fixed gcc 4.1 build (thank you vax)

tolerate NULL pointers at some places

Move insque/remque/lsearch/lfind from libcompat to libc,
they are in XPG4-UNIX, XSH5.0, mentioned in SUSv3 etc.
Minimal update of the manpages. (more needed)