hugetlb: restore interleaving of bootmem huge pages

I noticed that alloc_bootmem_huge_page() will only advance to the next
node on failure to allocate a huge page, potentially filling nodes with
huge-pages.  I asked about this on linux-mm and linux-numa, cc'ing the
usual huge page suspects.

Mel Gorman responded:

	I strongly suspect that the same node being used until allocation
	failure instead of round-robin is an oversight and not deliberate
	at all. It appears to be a side-effect of a fix made way back in
	commit 63b4613c ["hugetlb: fix
	hugepage allocation with memoryless nodes"]. Prior to that patch
	it looked like allocations would always round-robin even when
	allocation was successful.

This patch--factored out of my "hugetlb mempolicy" series--moves the
advance of the hstate next node from which to allocate up before the test
for success of the attempted allocation.

Note that alloc_bootmem_huge_page() is only used for order > MAX_ORDER
huge pages.

I'll post a s...