lib/sort.c: add _nonatomic() variants with cond_resched()

lib/sort.c: add _nonatomic() variants with cond_resched()

bcachefs calls sort() during recovery to sort all keys it found in the
journal, and this may be very large - gigabytes on large machines.

This has been causing "task blocked" warnings, so needs a
cond_resched().

[kent.overstreet@linux.dev: fix kerneldoc]
Link: https://lkml.kernel.org/r/cgsr5a447pxqomc4gvznsp5yroqmif4omd7o5lsr2swifjhoic@yzjjrx2bvrq7
Link: https://lkml.kernel.org/r/20250326152606.2594920-1-kent.overstreet@linux.dev
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Kuan-Wei Chiu <visitorckw@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>