Fix version check of fontforge.

Index: aclocal.m4
--- aclocal.m4.orig
+++ aclocal.m4
@@ -61,9 +61,7 @@ AC_DEFUN(STEPMAKE_GET_VERSION, [
     if test -z "$_ver"; then
         ## If empty, try date [fontforge]
         eval _ver=\"\`("$1" --version || "$1" -V) 2>&1 \
-        | grep '\(^\|[^0-9a-f]\)[0-9]\{6,8\}\([^0-9a-f]\|$\)' \
-        | head -n 1 \
-        | sed -e 's/^[^.0-9]*//' -e 's/[^.0-9]*$//'\`\"
+        | sed -ne 's/^libfontforge //p'\`\"
     fi
     echo "$_ver"
     changequote([, ])#dnl
