Expose an easy way in CLR hosting APIs to make shutdown work as in Desktop CLR

[muratg]

From aspnet/dnx#1589

using System;
using System.Threading;

namespace ConsoleApplication1
{
    internal class Program
    {
        public static void Main()
        {
            var t = new Thread(() => { while (true); });
            t.IsBackground = false;
            t.Start();
            Console.WriteLine("finished");
        }
    }
}

When ran with DNX, this has different behavior on CoreCLR and CLR. On CLR this waits forever, while on CoreCLR, it prints "finished" and exits immediately.

If there was a way to make hosting CoreCLR apps (which needed by DNX) behave the same on shutdown as Desktop CLR apps, we could make these behave the same.

[janvorli]

It looks like the mechanism is present even for CoreCLR, but never kicks in. The Assembly::ExecuteMainMethod calls RunMainPost method that is responsible for waiting for the other threads, but it calls it conditionally based on the stringArgs parameter being NULL or not being NULL.
On CoreCLR, the stringArgs is never NULL and so the wait is never executed.
It seems that adding a bool parameter to the ExecuteMainMethod that would indicate whether to wait or not instead of deriving it from the value of the stringArgs should fix the problem.

[janvorli]

Fixed by dotnet/coreclr#2164