If m4 doesn't support --version, try if gm4 does.

#--------------------------------------------------------------------------

# m4 check

#

m4=`${M4:-m4} --version 2>/dev/null|head -n 1`;

m4=`${M4:-m4} --version 2>/dev/null || ${M4:-gm4} --version 2>/dev/null | head -n 1`;

m4_version=`echo $m4 | sed -e 's/^.* \([0-9]\)/\1/' -e 's/[a-z]* *$//'`

if { echo $m4 | grep "GNU" >/dev/null 2>&1; } then