bug in 3.2 configure

[Herb Lewis]

The test for realpath is incorrect and causes a core dump at
least on FreeBSD and maybe others as well.

The following test program is used. The second argument
cannot be a NULL (this is what is causing the core).

#include <stdio.h>
#include <limits.h>
main() {
         char *newpath = realpath("/tmp", NULL);
         exit ((newpath != NULL) ? 0 : 1);
}

Both Linux and FreeBSD show the proto for realpath to be

char *realpath(const char *path, char *resolved_path);