Generating configure from configure.ac

While looking into this:
https://www.postgresql.org/message-id/20241119193121.7ba727c489b5f0b6d20f9c25%40sraoss.co.jp

I noticed that the patch for configure includes diffs against the
current configure script in the git repository in addition to his
changes to configure.ac.

@@ -14728,7 +14729,7 @@ else
We can't simply define LARGE_OFF_T to be 9223372036854775807,
since some C++ compilers masquerading as C compilers
incorrectly reject 9223372036854775807. */
-#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
+#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))

I ran autoconf 2.69 on my Ubuntu 20.04 laptop and got the same diffs
plus diffs related runstatedir:

+ --runstatedir=DIR modifiable per-process data [LOCALSTATEDIR/run]

If my understanding is correct, configure in the git repository has
been generated by autoconf 2.69 too. Maybe autoconf 2.69 generates
slightly different results depending on platform?

So my question is, are there any specific requirements for using
autoconf to generate configure from configure.ac besides the autoconf
version?

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp