Garbage contents after running autoconf 2.69

Hi all,

I was just modifying configure.in for another patch, then tried to
generate the new configure with autoconf on Debian. However I am
bumping into some noise in the process. First the state associated to
runstatedir support gets generated, which makes little sense for
Postgres as that's a path for installing data files modified by the
binaries run:
+ -runstatedir | --runstatedir | --runstatedi | --runstated \
+ | --runstate | --runstat | --runsta | --runst | --runs \
+ | --run | --ru | --r)
+ ac_prev=runstatedir ;;

Then I am getting some garbage for some of the macro definitions:
-#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))

Are usually those diffs just discarded manually before committing
patches? Or is there some specific configuration which can be used
with autoconf, in which case it would be interesting to document that
for developers?

Thanks,
--
Michael