From deraadt@ upstream:
Remove all getenv() calls, especially those wrapped by issetugid().
getenv()'s wrapped by issetugid() are safe, but issetugid() is ...
difficult to impliment on many operating systems. By accident, a grand
experiment was run over the last year, where issetugid() returned 1 (the
safe value) on a few operating systems. Noone noticed & complained that
certain environment variables were not working.......
Simplify autoconf checks by using AC_CHECK_FUNCS/HEADERS.
Clarify some ambiguous dependencies around strnlen/strndup.
Unconditionally enable pidwraptest for all arc4random implementations.
Remove HAVE_VASPRINTF conditional, since asprintf requires vasprintf.
ok @doug
This is to avoid redefining prototypes from the libc headers. Also,
simplify the autoconf function checks and remove some copy/paste
errors checking for 'write'.
ok wouter@