Linux powerpc new system call instruction and ABI

[Florian Weimer]

* Matheus Castanho via Libc-alpha:

> From: Nicholas Piggin <npiggin at gmail.com>
> Subject: [PATCH 1/1] powerpc: Fix handling of scv return error codes
>
> When using scv on templated ASM syscalls, current code interprets any
> negative return value as error, but the only valid error codes are in
> the range -4095..-1 according to the ABI.
>
> Reviewed-by: Matheus Castanho <msc at linux.ibm.com>

Please reference bug 27892 in the commit message.  I'd also appreciate a
backport to the 2.33 release branch (where you need to add NEWS manually
to add the bug reference).

Thanks,
Florian