Generate valid C++ for variadic functions

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

src/Generator/Generators/C/CppTypePrinter.cs

@@ -602,7 +602,9 @@ namespace CppSharp.Generators.C
             if (!string.IsNullOrEmpty(@return.Type))
                 @return.NamePrefix.Append(' ');
             @return.Name = @class + name;
-            @return.NameSuffix.Append('(').Append(@params).Append(')').Append(@const).Append(exceptionType);
+            @return.NameSuffix.Append('(').Append(@params)
+                .Append(function.IsVariadic ? ", ..." : string.Empty).Append(')')
+                .Append(@const).Append(exceptionType);
             return @return;
         }
 

tests/Common/Common.h

@@ -496,6 +496,12 @@ namespace SomeNamespace
     protected:
         void protectedInlined() {}
     };
+
+    class AbstractInlines
+    {
+    public:
+        virtual void hasVariadicArgs(int regular, ...) = 0;
+    };
 }
 
 // Test operator overloads