kernel/drivers/disk: enable Werror

* For NVMe library, disable warnings.
* Otherwise, change code to avoid generating warnings.
* No functional change.
* Fixes #9460.

Change-Id: Ia790de391e6b230c909dff7023f00a19bdd574be
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5284
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

Add a features.h to auto enable _DEFAULT_SOURCE

Unless __STRICT_ANSI__ is defined (as it is when running the compiler in
--std=c89 or --std=c99, but not when running it without any specific
args), we can enable these by default and behave like most other
systems. I don't know why no one has done this yet despite suggesting it
multiple times and people prefer to #define _BSD_SOURCE manually
everywhere.

Remove all places in our Jamfiles and sources where it had been defined.
_DEFAULT_SOURCE is now enabled by default for all sources of Haiku, since we
let the compiler use GNU extensions (no strict C standard specified on
command line)

Use _DEFAULT_SOURCE as the define name to match current versions of
glibc. Enable it if _BSD_SOURCE is #defined in compiler flags, for
backward compatibility.

Change-Id: I6db04da5f6db437723cdfba3478f5094a69d7727
Reviewed-on: https://review.haiku-os.org/c/1633
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

nvme: Import the driver code.

Only one qpair is used for reading, which is rather inefficient.
We currently allocate a bounce buffer for every allocation, which is
also inefficient, due to the fact that we must read an integer multiple
of LBAs.

But it does work, and it is actually reasonably fast, even on an emulated
machine using a spinning-disk-backed NVMe device (88MB/s.)

I wasn't able to get it working in non-packaged, though; the device manager
called supports_device() on a number of PCI devices, but not the NVMe
device, so I have a different version with a hack that grabs the PCI info
manually. I didn't test inside haiku.hpkg yet; perhaps it will work in there.