bug#23575: today's commit 374f6a5 makes flyspell highlight everything after end of line

[Jim Meyering]

Hi Paul,

Commit 374f6a5f34a83d3e4c518f0726558642293fdd71 "Port
--enable-gcc-warnings to GCC 6.1" has introduced a
flyspell-highlighting bug.

Reproduce with this:

  echo jj > k.texi; /p/p/emacs-2016-05-18.10h25/bin/emacs -nw -Q k.texi

When I then type 'flyspell-mode' and ENTER, I see the "jj" and the
rest of that line filled with red underscores.

Without that commit, flyspell-mode works as expected.