Copy syscall.tbl and syscallhdr.sh from linux/arch/ppc/kernel/syscalls v5.5
Update syscallhdr.sh to generate QEMU syscall_nr.h
and to not generate the entry if entry point is sys_ni_syscall.
Fix ppc/signal.c to define do_sigreturn() for TARGET_ABI32.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20200310103403.3284090-10-laurent@vivier.eu>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
