Convert PHI getIncomingValue() to foreach over incoming_values().  NFC.

We already had a method to iterate over all the incoming values of a PHI.  This just changes all eligible code to use it.

Ineligible code included anything which cared about the index, or was also trying to get the i'th incoming BB.

llvm-svn: 237169
diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index 8925e4c..0166935 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -755,8 +755,8 @@
         }
         case Instruction::PHI: {
           PHINode *PN = cast<PHINode>(RVI);
-          for (int i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
-            FlowsToReturn.insert(PN->getIncomingValue(i));
+          for (Value *IncValue : PN->incoming_values())
+            FlowsToReturn.insert(IncValue);
           continue;
         }