Clean up dead loops before suspend check elimination.

Get rid of BasicBlock::KillUnreachable() and just Kill()
unreachable blocks from the DFS order calculation.

Bug: 18718277
Change-Id: Icaf7b9c2320530e950f87e1e2e2bd1fa5f53cb98
diff --git a/compiler/dex/mir_graph.h b/compiler/dex/mir_graph.h
index 5c5d229..23bdd87 100644
--- a/compiler/dex/mir_graph.h
+++ b/compiler/dex/mir_graph.h
@@ -410,18 +410,12 @@
 
   /**
    * @brief Kill the BasicBlock.
-   * @details Unlink predecessors to make this block unreachable, then KillUnreachable().
+   * @details Unlink predecessors and successors, remove all MIRs, set the block type to kDead
+   *          and set hidden to true.
    */
   void Kill(MIRGraph* mir_graph);
 
   /**
-   * @brief Kill the unreachable block and all blocks that become unreachable by killing this one.
-   * @details Set the block type to kDead and set hidden to true, remove all MIRs,
-   *          unlink all successors and recursively kill successors that become unreachable.
-   */
-  void KillUnreachable(MIRGraph* mir_graph);
-
-  /**
    * @brief Is ssa_reg the last SSA definition of that VR in the block?
    */
   bool IsSSALiveOut(const CompilationUnit* c_unit, int ssa_reg);