Revert "[tools] Disable Objective-C exception handling for macOS .NET…

… apps due to a missing feature in the runtime. (xamarin#10123)"

This reverts commit 75979ca.

tools/common/Target.cs

@@ -613,12 +613,7 @@ void GenerateMacMain (StringWriter sw)
 			sw.WriteLine ("\txamarin_executable_name = \"{0}\";", App.AssemblyName);
 			if (!App.IsDefaultMarshalManagedExceptionMode)
 				sw.WriteLine ("\txamarin_marshal_managed_exception_mode = MarshalManagedExceptionMode{0};", App.MarshalManagedExceptions);
-#if NET
-			// We require support for dllmap, which isn't in .NET/macOS yet (https://github.com/dotnet/runtime/issues/43204), so disable
-			sw.WriteLine ("\txamarin_marshal_objectivec_exception_mode = MarshalObjectiveCExceptionModeDisable;");
-#else
 			sw.WriteLine ("\txamarin_marshal_objectivec_exception_mode = MarshalObjectiveCExceptionMode{0};", App.MarshalObjectiveCExceptions);
-#endif
 			if (App.DisableLldbAttach.HasValue ? App.DisableLldbAttach.Value : !App.EnableDebug)
 				sw.WriteLine ("\txamarin_disable_lldb_attach = true;");
 			if (App.DisableOmitFramePointer ?? App.EnableDebug)