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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158104 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGObjCGNU.cpp b/lib/CodeGen/CGObjCGNU.cpp
index e783eb7..e3ae237 100644
--- a/lib/CodeGen/CGObjCGNU.cpp
+++ b/lib/CodeGen/CGObjCGNU.cpp
@@ -1627,7 +1627,7 @@
          iter = PD->prop_begin(), endIter = PD->prop_end();
        iter != endIter ; iter++) {
     std::vector<llvm::Constant*> Fields;
-    ObjCPropertyDecl *property = &*iter;
+    ObjCPropertyDecl *property = *iter;
 
     Fields.push_back(MakeConstantString(property->getNameAsString()));
     Fields.push_back(llvm::ConstantInt::get(Int8Ty,
@@ -1878,7 +1878,7 @@
        iter != endIter ; iter++) {
     std::vector<llvm::Constant*> Fields;
     ObjCPropertyDecl *property = iter->getPropertyDecl();
-    ObjCPropertyImplDecl *propertyImpl = &*iter;
+    ObjCPropertyImplDecl *propertyImpl = *iter;
     bool isSynthesized = (propertyImpl->getPropertyImplementation() == 
         ObjCPropertyImplDecl::Synthesize);