[PREEMPT RT] SLUB and split softirq lock for v3.4-rt

3.4-rt which lacks two RT features from 3.6: SLUB support and the split softirq lock implementation. SLUB has a way better performance than SLAB on RT and the split softirq lock implementation is necessary especially for realtime networking applications. The following patch series backports

[PREEMPT RT] SLUB and split softirq lock for v3.4-rt

3.4-rt which lacks two RT features from 3.6: SLUB support and the split softirq lock implementation. SLUB has a way better performance than SLAB on RT and the split softirq lock implementation is necessary especially for realtime networking applications. The following patch series backports