Enable Load Store Elimination for ARM and ARM64

This patch refactors the implementation of the LoadStoreElimination
optimisation pass. Please note that this pass was disabled and not
functional for any of the backends.

The current implementation tracks aliases and handles DalvikRegs as well
as Heap memory regions. It has been tested and it is known to optimise
out the following:
  * Load - Load
  * Store - Load
  * Store - Store
  * Load Literals

Change-Id: Iefae9b696f87f833ef35c451ed4d49c5a1b6fde0