SIL optimizer: add an additional LICM pass to the pipeline.

The COWOpts optimization relies more on LICM. This additional run of the pass ensures that there is no phase ordering issue between LICM and COWOpts

Author: eeckstein

lib/SILOptimizer/PassManager/PassPipeline.cpp

@@ -515,6 +515,7 @@ static void addMidLevelFunctionPipeline(SILPassPipelinePlan &P) {
   P.addLICM();
   // Run loop unrolling after inlining and constant propagation, because loop
   // trip counts may have became constant.
+  P.addLICM();
   P.addLoopUnroll();
 }