Allow BPs before host has initialized during mixed mode debugging

@mikem8361 commented on [Fri Mar 23 2018](https://github.com/dotnet/coreclr/issues/17153)

Yes, interop debugging is .NET Core has the restriction that you cannot hit breakpoints in native code before the .NET runtime starts.

@mikem8361 is there an issue that tracks removing that restriction?

Fixing this would require a major architectural change to how interop debugging works, so I don't think it will be resolved any time soon. I would probably recomend switching back and forth between your C++ project and your .NET Core project depending on which type of code you want to debug. This is what I do all the time while debugging the .NET Core debugger (which has lots of both C# and C++ code).

See #16776