Fix incorrect handling of private ctors

In cases where a factory new method is available on a type, we should not even be attempting to invoke that type's constructor, because the constructor may be private or might not even exist.

Eliminate any instantiations of templates that attempt such invocation.

src/autowiring/test/AutoConstructTest.cpp

@@ -58,4 +58,28 @@ TEST_F(AutoConstructTest, CanConstructRvalueCtor) {
 
 TEST_F(AutoConstructTest, CanCopyAutoConstruct) {
   AutoConstruct<HasDefaultCtorAndOthers> v(100);
-}
+}
+
+namespace {
+  class MyPrivateCtorClass {
+    MyPrivateCtorClass(void):
+      ival(-10)
+    {}
+    MyPrivateCtorClass(int ival) :
+      ival(ival)
+    {}
+
+  public:
+    const int ival;
+
+    static MyPrivateCtorClass* New(int ival) {
+      return new MyPrivateCtorClass{ ival };
+    }
+  };
+}
+
+TEST_F(AutoConstructTest, FactoryNewPrivateCtor) {
+  AutoConstruct<MyPrivateCtorClass> mpcc{ 1002 };
+  ASSERT_NE(nullptr, mpcc.get()) << "Null not expected as a return type from a factory new construction";
+  ASSERT_EQ(1002, mpcc->ival) << "Correct ctor was not invoked on a type with a private ctor";
+}