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
* use the original name for the file from OpenSSH (remove duplicate version)
* add va_copy/__va_copy checks to configure
* incorporate proposed fixes to openssh version:
+ include more system headers directly for various definitions
+ limit the scope of va_copy/va_end to their affected vsnprintf calls
+ simplify error handling, removing a dead assignment