lib-fs-resize: rewrite ped_file_system_clobber

lib-fs-resize: rewrite ped_file_system_clobber

Before, it would probe for an existing file system type and then,
according to what it found, call the corresponding <FS_TYPE>_clobber
function.  Now that we have restored only HFS and FAT FS-writing
support, only those few types have a corresponding _clobber function.
We would obviously fail to clear common types of file systems, and even
if we were to restore all previous _clobber functions, none of those
were able to handle sector sizes larger than 512.  Not worth it.
* libparted/fs/r/filesys.c: Include pt-tools.h.
(MIN): Define.
(ped_file_system_clobber): Rewrite not to use hfs*_clobber or
fat_clobber.  Instead, simply clear the first three and last two
sectors of the specified "device".
* libparted/fs/Makefile.am (INCLUDES): Add
-I$(top_srcdir)/libparted/labels for new use of a ptt_* function.