Revert Decl's iterators back to pointer value_type rather than reference value_type

In addition, I've made the pointer and reference typedef 'void' rather than T*
just so they can't get misused. I would've omitted them entirely but
std::distance likes them to be there even if it doesn't use them.

This rolls back r155808 and r155869.

Review by Doug Gregor incorporating feedback from Chandler Carruth.

llvm-svn: 158104
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index d53cbc4..7b0e0f5 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -352,7 +352,7 @@
     return;
   }
   LValue DestLV = CGF.MakeNaturalAlignAddrLValue(destPtr, initList->getType());
-  LValue start = CGF.EmitLValueForFieldInitialization(DestLV, &*field);
+  LValue start = CGF.EmitLValueForFieldInitialization(DestLV, *field);
   llvm::Value *arrayStart = Builder.CreateStructGEP(alloc, 0, "arraystart");
   CGF.EmitStoreThroughLValue(RValue::get(arrayStart), start);
   ++field;
@@ -361,7 +361,7 @@
     CGF.ErrorUnsupported(initList, "weird std::initializer_list");
     return;
   }
-  LValue endOrLength = CGF.EmitLValueForFieldInitialization(DestLV, &*field);
+  LValue endOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *field);
   if (ctx.hasSameType(field->getType(), elementPtr)) {
     // End pointer.
     llvm::Value *arrayEnd = Builder.CreateStructGEP(alloc,numInits, "arrayend");
@@ -1005,7 +1005,7 @@
       break;
     
 
-    LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, &*field);
+    LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, *field);
     // We never generate write-barries for initialized fields.
     LV.setNonGC(true);