Changes to automatically enable large file support on some systems.
I believe this works on Linux (tested both on a system with large file
support and one without it), and it may work on Solaris 2.7.

The changes are twofold:

(1) The configure script now boldly tries to set the two symbols that
    are recommended (for Solaris and Linux), and then tries a test
    script that does some simple seeking without writing.

(2) The _portable_{fseek,ftell} functions are a little more systematic
    in how they try the different large file support options: first
    try fseeko/ftello, but only if off_t is large; then try
    fseek64/ftell64; then try hacking with fgetpos/fsetpos.

I'm keeping my fingers crossed.  The meaning of the
HAVE_LARGEFILE_SUPPORT macro is not at all clear.

I'll see if I can get it to work on Windows as well.
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 14fb375..255a983 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -90,6 +90,9 @@
 /* Defined on Solaris to see additional function prototypes. */
 #undef __EXTENSIONS__
 
+/* This must be set to 64 on some systems to enable large file support */
+#undef _FILE_OFFSET_BITS
+
 /* Define if getpgrp() must be called as getpgrp(0). */
 #undef GETPGRP_HAVE_ARG
 
@@ -166,6 +169,9 @@
 /* Define if the compiler provides a wchar.h header file. */
 #undef HAVE_WCHAR_H
 
+/* This must be defined on some systems to enable large file support */
+#undef _LARGEFILE_SOURCE
+
 /* Define if you want to have a Unicode type. */
 #undef Py_USING_UNICODE
 
@@ -716,10 +722,3 @@
 #define DL_EXPORT(RTYPE) __declspec(dllexport) RTYPE
 #endif
 #endif
-
-/* Define the macros needed if on a UnixWare 7.x system. */
-#if defined(__USLC__) && defined(__SCO_VERSION__)
-#define SCO_ACCEPT_BUG     /* Use workaround for UnixWare accept() bug */
-#define SCO_ATAN2_BUG      /* Use workaround for UnixWare atan2() bug */
-#define STRICT_SYSV_CURSES /* Don't use ncurses extensions */
-#endif