Thanks for sending the extra data. Oh, I see you are running GCC 5.4.
You have run into a GCC bug that I just now filed here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107116
This bug was in GCC 5 and is still present in GCC 12.
To work around the GCC bug, please use './configure
--disable-gcc-warnings' instead of plain './configure'. Or (and this may
be simpler) please use the latest coreutils release from
<https://ftp.gnu.org/gnu/coreutils/> rather than trying to bootstrap.
Another possibility is to upgrade to GCC 7 (2017) or later, as these GCC
versions have __builtin_sub_overflow which means the code in question
will not be compiled.
I doubt whether we should modify Gnulib or coreutils to work around the
GCC bug, as we expect developers who are bootstrapping to use up-to-date
tools and GCC 6 is not up-to-date. I'm therefore closing the coreutils
bug report.