Catch up with all the lint warnings since exit on warning was disabled.
Disable 'missing header declaration' and 'nested extern' warnings for now.

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

branches: 1.9.44;
cleanup casts and KNF.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22280, verified by myself.

Don't acquire __environ_lock around exec*() calls; nothing requires
that these calls be thread-safe with respect to the environment, and it
causes serious problems for threaded applications which call vfork() and
exec*() (including indirectly, via popen() or system()).

Acquire and release __environ_lock in the parent in popen() and system() to
play safe and provide the child with a stable environment.

__environ_lock should also have an atfork() handler; still under development.

Merge the nathanw_sa branch.

branches: 1.5.6;
Delint.
Remove trailing ; from uses of __weak_alias(). The macro inserts this if
needed.

Add a multiple-reader/single-writer lock to protect environ.

If port provides __weak_alias(), provide an Standard C and POSIX pure
identifier namespace by renaming non standard functions and variables
such that they have a leading underscore. The library will use those
names internally. Weak aliases are used to provide the original names
to the API.

This is only the first part of this change. It is most of the functions
which are implemented in C for all NetBSD ports. Subsequent changes are
to add the same support to the remaining C files, to assembly files, and
to the automagically generated assembly source used for system calls.
When all of the above is done, ports with weak alias support should add
a definition for __weak_alias to <sys/cdefs.h>.

Fix RCSID's

branches: 1.1.2;
Split all exec*() functions out of exec.c into their own files.