Generate valid C++ for protected ctors of pure classes

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/Generator/Passes/SymbolsCodeGenerator.cs

@@ -157,12 +157,12 @@ namespace CppSharp.Passes
                 Write("extern \"C\" ");
             Write($"{GetExporting()}void {wrapper}({signature}) ");
 
-            if (method.Access == AccessSpecifier.Protected ||
-                ((Class) method.Namespace).IsAbstract)
+            bool isAbstract = ((Class) method.Namespace).IsAbstract;
+            if (method.Access == AccessSpecifier.Protected || isAbstract)
             {
                 Write($@"{{ ::new ({Helpers.InstanceField}) {
                     wrapper}{method.Namespace.Name}({@params}); }}");
-                WriteLine(method.Access == AccessSpecifier.Protected ? " };" : string.Empty);
+                WriteLine(!isAbstract ? " };" : string.Empty);
             }
             else
             {

tests/CSharp/CSharp.cpp

@@ -832,10 +832,6 @@ int MethodsWithDefaultValues::getA()
     return m_foo.A;
 }
 
-HasPureVirtualWithDefaultArg::~HasPureVirtualWithDefaultArg()
-{
-}
-
 HasOverridesWithChangedAccessBase::HasOverridesWithChangedAccessBase()
 {
 }

tests/CSharp/CSharp.h

@@ -489,11 +489,14 @@ private:
     Foo m_foo;
 };
 
-class DLL_API HasPureVirtualWithDefaultArg
+// don't export this one or the bug doesn't reproduce on windows
+class HasPureVirtualWithDefaultArg
 {
 public:
-    virtual ~HasPureVirtualWithDefaultArg();
+    virtual ~HasPureVirtualWithDefaultArg() {}
     virtual void pureVirtualWithDefaultArg(Foo* foo = nullptr) = 0;
+protected:
+    HasPureVirtualWithDefaultArg() {}
 };
 
 class DLL_API HasOverridesWithChangedAccessBase