MORE Add fsal_filesystem object and supporting commonlib code

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/FSAL_VFS/export.c

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/FSAL_VFS/handle.c

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/FSAL_VFS/handle_syscalls.c

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/FSAL_VFS/os/freebsd/handle_syscalls.c

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/FSAL_VFS/os/linux/handle_syscalls.c

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/FSAL_VFS/vfs_methods.h

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/FSAL_VFS/xfs/handle_syscalls.c

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
FSAL/Stackable_FSALs/FSAL_NULL/export.c

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
include/fsal_api.h

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>