Address comments from swiftlang#33504

Author: meg-gupta

lib/SILOptimizer/ARC/ARCSequenceOptUtils.h

@@ -21,7 +21,7 @@
 #include "swift/SIL/SILInstruction.h"
 
 namespace swift {
-  bool isARCSignificantTerminator(TermInst *TI);
+bool isARCSignificantTerminator(TermInst *TI);
 } // end namespace swift
 
 #endif

lib/SILOptimizer/ARC/GlobalARCSequenceDataflow.cpp

@@ -222,10 +222,8 @@ bool ARCSequenceDataflowEvaluator::processBBBottomUp(
       SetFactory);
 
   auto II = BB.rbegin();
-  if (isa<TermInst>(*II)) {
-    if (!isARCSignificantTerminator(&cast<TermInst>(*II))) {
-      II++;
-    }
+  if (!isARCSignificantTerminator(&cast<TermInst>(*II))) {
+    II++;
   }
 
   // For each instruction I in BB visited in reverse...