Bug when decorating an overloaded function

[yloiseau]

This is probably linked to #326 in some way...

given test.golo as:

module golo.bugs.test.OverloadedDecoration

function idDeco = |f| -> f

@idDeco
function foo = |a| -> "foo: " + a

@idDeco
function foo = |a, b| -> "foo2: " + a + b

function main = |args| {
  println(foo(42))
  println(foo(4, 2))
}

then:

$ golo golo --files test.golo 
Exception in thread "main" java.lang.invoke.WrongMethodTypeException: cannot convert MethodHandle(Object,Object)Object to (Object)Object
	at java.lang.invoke.MethodHandle.asTypeUncached(MethodHandle.java:775)
	at java.lang.invoke.MethodHandle.asType(MethodHandle.java:761)
	at java.lang.invoke.Invokers.checkGenericType(Invokers.java:321)
	at java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:627)
	at org.eclipse.golo.runtime.FunctionCallSupport.fallback(FunctionCallSupport.java:196)

[yloiseau]

cc @Artpej