compat: consolidate the compat_flock{,64} definition

compat: consolidate the compat_flock{,64} definition

Provide a single common definition for the compat_flock and
compat_flock64 structures using the same tricks as for the native
variants.  Another extra define is added for the packing required on
x86.

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
Tested-by: Heiko Stuebner <[email protected]>
Acked-by: Helge Deller <[email protected]>  # parisc
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>