FSharpType overrides GetHashCode causing infinite loop

[fsoikin]

This line:

       override x.GetHashCode() = hash x

hash goes to Microsoft.FSharp.Core.LanguagePrimitives.HashCompare.GenericHashIntrinsic<'t>, which does a few checks and, having confirmed that FSharpType does not implement IStructuralEquatable, falls straight back to Object.GetHashCode, thus looping the sequence.

Because all these calls are tail calls, this doesn't even cause a StackOverflowException, simply hangs up forever.