ANDROID: ARM: fiq_debugger: Add generic fiq serial debugger

Change-Id: Ibb536c88f0dbaf4766d0599296907e35e42cbfd6
Signed-off-by: Iliyan Malchev <malchev@google.com>
Signed-off-by: Arve Hjønnevåg <arve@android.com>

[AmitP: Upstream commit 2a1f062a ("sched/headers: Move signal wakeup &
        sigpending methods from <linux/sched.h> into <linux/sched/signal.h>")
        moved few signal definitions to <linux/sched/signal.h>. Hence include
        that instead of <linux/sched.h>.

        Also folded following android-4.9 commit changes into this patch
        69279c68eed4 ("ANDROID: ARM: fiq_debugger: fix compiling for v3.3")
        d05890d37ecc ("ANDROID: ARM: fiq_debugger: Fix to compile on 3.7")
        9de62e0d3f24 ("ANDROID: ARM: fiq_debugger: Use kmsg_dumper to dump kernel logs")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>