Avoid waiting on physical allocations that can't possibly be satisfied

• Change vm_page_reclaim_contig[_domain] to return an errno instead of a boolean. 0 indicates a successful reclaim, ENOMEM indicates lack of available memory to reclaim, with any other error (currently only ERANGE) indicating that reclamation is impossible for the specified address range. Change all callers to only follow up with vm_page_wait* in the ENOMEM case.

• Introduce vm_domainset_iter_ignore(), which marks the specified domain as unavailable for further use by the iterator. Use this function to ignore domains that can't possibly satisfy a physical allocation request. Since WAITOK allocations run the iterators repeatedly, this avoids the possibility of infinitely spinning in domain iteration if no available domain can satisfy the allocation request.

PR: 274252
Reported by: kevans
Tested by: kevans
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D42706

(cherry picked from commit 2619c5ccfe1f7889f0241916bd17d06340142b05)

MFCed as a prerequisite for further MFC of VM domainset changes. Based
on analysis, it would not hurt, and I have been using it in productions
for months now.

Resolved the trivial conflict due to commit 718d1928f874 ("LinuxKPI:
make linux_alloc_pages() honor __GFP_NORETRY") having been MFCed before
this one.