Prevented a crash in the tests on Mono because of a Mono bug.

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

src/Core/Platform.cs

@@ -50,7 +50,7 @@ namespace CppSharp
 
         public static bool IsMono
         {
-            get { return System.Type.GetType("Mono.Runtime") == null; }
+            get { return Type.GetType("Mono.Runtime") != null; }
         }
     }
 }

src/Generator.Tests/GeneratorTest.cs

@@ -39,7 +39,7 @@ namespace CppSharp.Utils
 
             // Workaround for CLR which does not check for .dll if the
             // name already has a dot.
-            if (Platform.IsMono)
+            if (!Platform.IsMono)
                 options.SharedLibraryName += ".dll";
 
             var path = Path.GetFullPath(GetTestsDirectory(name));

tests/CSharpTemp/CSharpTemp.Tests.cs

@@ -60,6 +60,11 @@ public class CSharpTempTests : GeneratorTestFixture
     [Test]
     public void TestMultipleInheritance()
     {
+        // TODO: remove when the bug in question is fixed
+        if (Type.GetType("Mono.Runtime") != null)
+        {
+            Assert.Fail("Crashes with Mono because of a problem with marshalling arrays: https://gist.github.com/tritao/7e62c71ffe57d6bc326e");
+        }
         using (var baz = new Baz())
         {
             Assert.That(baz.Method, Is.EqualTo(1));