removing the final vestiges of the jm_ prefix from gnulib

[Jim Meyering]

There are still a bunch cache variables with my jm_ prefix.
I'm about to change them all to use gl_ instead.
The only risk is that some other project is using the jm_-prefixed
variable names (most likely in configure.ac).  There *are* two uses
in coreutils configure.ac, but that's not surprising, since they
came from there originally.

Here's what I'm doing to make the change:

Run this in gnulib:
  perl -pi -e 's/\bjm_/gl_/g' $(grep -l jm_ m4/*.m4)

Convert the two uses in coreutils (outside of ChangeLog files):
  perl -pi -e 's/\bjm_/gl_/g' configure.ac

If anyone has checked out copies of all projects using gnulib,
it'd be nice to follow the instructions below for each project.
I've checked a few that I had handy and found no other uses.

Run these commands to see if there are stray uses of
the symbols I'm renaming:

cat <<EOF > /tmp/jm-syms
jm_ac_cv_func_link_follows_symlink
jm_cv_func_strtoimax_macro
jm_cv_func_strtoumax_macro
jm_cv_func_svid_putenv
jm_cv_func_unlink_busy_text
jm_cv_have_proc_uptime
jm_cv_struct_dirent_d_type
jm_cv_sys_struct_winsize_needs_sys_ptem_h
jm_cv_sys_tiocgwinsz_needs_sys_ioctl_h
jm_cv_sys_tiocgwinsz_needs_termios_h
EOF
grep -lrF -f /tmp/jm-syms . | grep -vE \
'/(d-type|jm-winsz[12]|link-follow|putenv|strto[iu]max|unlink-busy|uptime)\.m4$'\
  | grep -vE '/(autom4te.cache/.*|configure|config.log)$'

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If that lists any files using those jm_ variables, please let me know.