* m4/macros/header_templates.m4: templates for FFS.

* m4/macros/header_templates.m4: templates for FFS.

* m4/macros/check_mnttab_type.m4: on BSD44 systems, check for file
system mount table name via the MOUNT_* mount(2) macros (because
BSD44 keeps the mount table in the kernel).

* configure.in: synchronise order of searching for mnttab entries
and mount names.  The new order is "ext3 ext2 ffs ufs 4.2 4.3 4.4
efs xfs jfs ultrix" (which would prefer ffs on BSD44 instead of
ufs, and ext3 instead of ext2 on Linux).