The added file is taken from gnulib e313a53; adding it fixes the
following warning:
configure.ac:225: warning: gl_HOST_CPU_C_ABI_32BIT is m4_require'd but not m4_defun'd
The missing file also caused the generated `configure` script to
contain an reference to `gl_HOST_CPU_C_ABI_32BIT`, instead of its
expansion.
Andreas Rottmann