sh: Make syscall tracer use tracehook notifiers, add TIF_NOTIFY_RESUME.

sh: Make syscall tracer use tracehook notifiers, add TIF_NOTIFY_RESUME.

This follows the changes in commits:

706c581803cf3af6465bdfeda43222144fb1aa09
552ebc06deb53672d92defa4c0b8cb4b55985b7b

on powerpc. Adding in TIF_NOTIFY_RESUME, and cleaning up the syscall
tracing to be more generic. This is an incremental step to turning
on tracehook, as well as unifying more of the ptrace and signal code
across the 32/64 split.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>