Revert "Remove two runs of the passes in AddSSAPasses."

This reverts commit b00dcbe due to a
test failure.

Author: rudkx

lib/SILOptimizer/PassManager/Passes.cpp

@@ -274,6 +274,7 @@ void swift::runSILOptimizationPasses(SILModule &Module) {
   PM.setStageName("HighLevel");
   AddSSAPasses(PM, OptimizationLevelKind::HighLevel);
   PM.runOneIteration();
+  PM.runOneIteration();
   PM.resetAndRemoveTransformations();
 
   PM.setStageName("EarlyLoopOpt");
@@ -293,6 +294,7 @@ void swift::runSILOptimizationPasses(SILModule &Module) {
   PM.setStageName("MidLevel");
   AddSSAPasses(PM, OptimizationLevelKind::MidLevel);
   PM.runOneIteration();
+  PM.runOneIteration();
   PM.resetAndRemoveTransformations();
 
   // Perform lowering optimizations.