Configure tweaks.

Configure tweaks.

Fix the Unixware/SCO uname scan:

From: Tom Hughes <thh@cyberscience.com>
To: perlbug@perl.com
Subject: Not OK: perl 5.00555 on i386-svr4 [actually Unixware 2.1] (UNINSTALLED)
Date: 17 Feb 1999 15:34:15 +0000
Message-ID: <yekg185nix4.fsf@elva.cyberscience.com>

AIX syscalls.exp scan: the syscall might be marked 32, 3264, or 64

From: Joe Buehler <jhpb@hekimian.com>
To: perl5-porters@perl.org
Subject: setsid not detected by perl 5.005_02 configure under AIX 4.3
Date: 12 Feb 1999 11:25:21 -0500
Message-ID: <yd3lni3613i.fsf@ganymede.hekimian.com>

Make the pthreads joinable constant scan to output to fd 4, not 2.

p4raw-id: //depot/cfgperl@2965