perl 4.0 patch 19: (combined patch)

perl 4.0 patch 19:  (combined patch)

Ok, here's the cleanup patch I suggested you wait for.  Have at it...

Subject: added little-endian pack/unpack options

This is the only enhancement in this patch, but it seemed unlikely
to bust anything else, and added functionality that it was very
difficult to do any other way.  Compliments of David W. Sanderson.

Subject: op/regexp.t failed from missing arg to bcmp()
Subject: study was busted by 4.018
Subject: sort $subname was busted by changes in 4.018
Subject: default arg for shift was wrong after first subroutine definition

Things that broke in 4.018.  Shame on me.

Subject: do {$foo ne "bar";} returned wrong value

A bug of long standing.  How come nobody saw this one?  Or if you
did, why didn't you report it before now?  Or if you did, why did
I ignore you?  :-)

Subject: some machines need -lsocket before -lnsl
Subject: some earlier patches weren't propagated to alternate 286 code
Subject: compile in the x2p directory couldn't find cppstdin
Subject: more hints for aix, isc, hp, sco, uts
Subject: installperl no longer updates unchanged library files
Subject: uts wrongly defines S_ISDIR() et al
Subject: too many preprocessors can't expand a macro right in #if

The usual pastiche of portability kludges.

Subject: deleted some unused functions from usersub.c

And fixed the spelling of John Macdonald's name, and included his
suggested workaround for a certain vendor's stdio bug...

Subject: added readdir test
Subject: made op/groups.t more reliable
Subject: added test for sort $subname to op/sort.t
Subject: added some hacks to op/stat.t for weird filesystem architectures

Improvements (hopefully) to the regression tests.