Switch more loops to be range-based

This makes the code a little more concise, no functional change is
intended.

llvm-svn: 273644
diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
index 52beb15..e73d28f 100644
--- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
@@ -192,8 +192,8 @@
       }
     // Remove incoming values in the reverse order to prevent invalidating
     // *successive* index.
-    for (auto III = Indices.rbegin(), IIE = Indices.rend(); III != IIE; ++III)
-      PN->removeIncomingValue(*III);
+    for (unsigned III : reverse(Indices))
+      PN->removeIncomingValue(III);
   }
 }