[klibc] signal: Add sysconfig setting to force SA_SIGINFO on

[klibc] signal: Add sysconfig setting to force SA_SIGINFO on

Origin: https://git.kernel.org/pub/scm/libs/klibc/klibc.git/commit/?id=2a2a0b6b79c2470f529daabd5c193f58fe188337

On alpha, arm, i386, m68k, powerpc, s390, sh, and sparc (32-bit), the
kernel sets up the signal stack frame differently depending on the
SA_SIGINFO flag, not whether the sigaction() or rt_sigaction() system
call was used to install the handler.

On alpha and sparc, we are going to start providing our own restorer
that will call rt_sigaction(), so will need to ensure this flag is
always set.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Gbp-Pq: Name 0002-klibc-signal-Add-sysconfig-setting-to-force-SA_SIGIN.patch