[V2] arch/powerpc: use BUILD_BUG_ON_MSG() when detect unfit {cmp}xchg size

[Michael Ellerman]

On Tue, 2016-23-02 at 11:05:01 UTC, xinhui wrote:
> From: pan xinhui <xinhui.pan at linux.vnet.ibm.com>
> 
> __xchg_called_with_bad_pointer() can't tell us what codes use {cmp}xchg
> in incorrect way.  And no error will be reported until the link stage.
> To fix such a kind of issues easily, we use BUILD_BUG_ON_MSG() here.
> 
> Signed-off-by: pan xinhui <xinhui.pan at linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/10d8b1480e6966ba03cd3afad3

cheers