Fix a crash when a function pointer is a template arg

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

src/Generator/Generators/CSharp/CSharpTypePrinter.cs

@@ -157,6 +157,9 @@ namespace CppSharp.Generators.CSharp
             return base.VisitBuiltinType(builtin, quals);
         }
 
+        public override TypePrinterResult VisitFunctionType(FunctionType function, TypeQualifiers quals)
+            => IntPtrType;
+
         private bool allowStrings = true;
 
         public override TypePrinterResult VisitPointerType(PointerType pointer,

tests/CSharp/CSharpTemplates.h

@@ -715,7 +715,7 @@ void forceUseSpecializations(IndependentFields<int> _1, IndependentFields<bool>
                              TemplateDerivedFromRegularDynamic<RegularDynamic> _14,
                              IndependentFields<OnlySpecialisedInTypeArg<double>> _15,
                              DependentPointerFields<float> _16, IndependentFields<const T1&> _17,
-                             TemplateWithIndexer<T2*> _18, std::string s);
+                             TemplateWithIndexer<T2*> _18, IndependentFields<int(*)(int)>, std::string s);
 
 void hasIgnoredParam(DependentValueFields<IndependentFields<Ignored>> ii);