kernel: backport fib_trie improvements/fixes from 4.0-rc

...ib_trie-Fix-proc-net-fib_trie-when-CONFIG_IP_MULTIP.patch

...ib_trie-Fix-trie-balancing-issue-if-new-node-pushes.patch

...ib_trie-Update-usage-stats-to-be-percpu-instead-of-.patch

...18/080-03-fib_trie-Make-leaf-and-tnode-more-uniform.patch

...ib_trie-Merge-tnode_free-and-leaf_free-into-node_fr.patch

.../patches-3.18/080-05-fib_trie-Merge-leaf-into-tnode.patch

...ib_trie-Optimize-fib_table_lookup-to-avoid-wasting-.patch

...patches-3.18/080-07-fib_trie-Optimize-fib_find_node.patch

...ches-3.18/080-08-fib_trie-Optimize-fib_table_insert.patch

...ib_trie-Update-meaning-of-pos-to-represent-unchecke.patch

...ib_trie-Use-unsigned-long-for-anything-dealing-with.patch

...80-11-fib_trie-Push-rcu_read_lock-unlock-to-callers.patch

.../080-12-fib_trie-Move-resize-to-after-inflate-halve.patch

...ib_trie-Add-functions-should_inflate-and-should_hal.patch

...ib_trie-Push-assignment-of-child-to-parent-down-int.patch

...-fib_trie-Push-tnode-flushing-down-to-inflate-halve.patch

...ib_trie-inflate-halve-nodes-in-a-more-RCU-friendly-.patch

...ib_trie-Remove-checks-for-index-tnode_child_length-.patch

...80-18-fib_trie-Add-tracking-value-for-suffix-length.patch

...ib_trie-Fix-RCU-bug-and-merge-similar-bits-of-infla.patch