UBUNTU: SAUCE: Yama: add PTRACE exception tracking and interface

UBUNTU: SAUCE: Yama: add PTRACE exception tracking and interface

Some application suites have external crash handlers that depend on
being able to use PTRACE to generate crash reports (KDE, Chromium, etc).
Since the inferior process generally knows the PID of the debugger,
it can use PR_SET_PTRACER to allow a specific PID and its descendants
to perform the PTRACE instead of only a direct ancestor.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: Leann Ogasawara <leann.ogasawara@canonical.com>