This reverts commit df8c3deb from six years ago, which prevented a crash
on the Armel/Maemo platforms but causes nano to lose history items.

The strncmp() function on those platforms treats size_t numbers with
the high bit set as if they were zero.  To avoid that, use a number
that cannot be seen as negative, as suggested by <alpha@qzx.com>.

This fixes https://savannah.gnu.org/bugs/?48048

.
Tested-by: Tito Ragusa <farmatito@tiscali.it>
Signed-off-by: Benno Schulenberg <bensberg@justemail.net>