What is the alignment of padding layouts?

Currently, padding layouts are just like value layouts - e.g. their inferred padding is == to their size.

In cases like these:

    public static final MemoryLayout foo$LAYOUT = MemoryLayout.ofStruct(
        MemoryLayouts.SysV.C_BOOL.withName("x"),
        MemoryLayout.ofPaddingBits(56),
        MemoryLayouts.SysV.C_INT.withName("v"),
        MemoryLayout.ofPaddingBits(32)
    ).withName("foo");

This is problematic, because here we would have that the padding layout has an alignment of 56 - which will give the struct itself an alignment of 56 - since the struct size is 128 and 128 is not a multiple of 56, this layout is not considered to be well-formed by MemorySegment::allocateNative.