-lc fix for BSD/OS and FreeBSD

[Dave MacKenzie]

I was trying to run a CGI program with Apache 2.0.18 on BSDI BSD/OS 4.3,
and found that when read() on a nonblocking pipe returned -1, errno wasn't
setting set (to EAGAIN); it was 0.  So apache didn't do its timeout call
and the CGI request got a Server Error.

The problem turned out to be that when linking libapr.so, libtool was adding
-lc.  Then, when libapr.so was linked into httpd, -lc gets linked in again,
and there are now two copies of libc in apache's address space, each with its
own thread-safe copy of errno.

The version of libtool that came with Apache is:

ltmain.sh (GNU libtool) 1.3.4-freebsd-ports (1.385.2.196 1999/12/07 21:47:57)

However, the problem still exists in:

ltmain.sh (GNU libtool) 1.4 (1.920 2001/04/24 23:26:18)

The latter contains this case:

          *-*-netbsd*)
            # Don't link with libc until the a.out ld.so is fixed.
            ;;

That case needs to be extended to:

          *-*-netbsd* | *-*-freebsd* | *-*-bsdi4*)
            # Don't link with libc until the a.out ld.so is fixed.
            ;;

The FreeBSD port of libtool adds freebsd, and as I just discovered,
BSD/OS needs the same treatment.

This problem also recently bit Steven Schultz <address@hidden> while
porting some video software from Linux to BSD/OS.