mm, compaction: rework compact_should_abort as compact_check_resched

With incremental changes, compact_should_abort no longer makes any
documented sense.  Rename to compact_check_resched and update the
associated comments.  There is no benefit other than reducing redundant
code and making the intent slightly clearer.  It could potentially be
merged with earlier patches but it just makes the review slightly
harder.

Link: http://lkml.kernel.org/r/20190118175136.31341-17-mgorman@techsingularity.net


Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>