configs: introduce debug.config for CI-like setup

configs: introduce debug.config for CI-like setup

Some general debugging features like kmemleak, KASAN, lockdep, UBSAN etc
help fix many viruses like a microscope.  On the other hand, those
features are scatter around and mixed up with more situational debugging
options making them difficult to consume properly.  This cold help amplify
the general debugging/testing efforts and help establish sensitive default
values for those options across the broad.  This could also help different
distros to collaborate on maintaining debug-flavored kernels.

The config is based on years' experiences running daily CI inside the
largest enterprise Linux distro company to seek regressions on linux-next
builds on different bare-metal and virtual platforms.  It can be used for
example,

$ make ARCH=arm64 defconfig debug.config

Since KASAN and KCSAN can't be enabled together, we will need to create a
separate one for KCSAN later as well.

Link: https://lkml.kernel.org/r/20211115134754.7334-1-quic_qiancai@quicinc.com
Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: "Stephen Rothwell" <sfr@canb.auug.org.au>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>