Set Antlr3.exe.config to enable multi-targeting compatibility with .NET 4.0 framework

Author: ngbrown

Tools/Antlr/Antlr3.exe.config

@@ -1,3 +1,7 @@
 <?xml version="1.0"?>
 <configuration>
-	<startup><supportedRuntime version="v2.0.50727" sku="Client"/></startup></configuration>
+	<startup>
+		<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0,Profile=Client"/>
+		<supportedRuntime version="v2.0.50727" sku="Client"/>
+	</startup>
+</configuration>