Adding the functions as initfunc in module init table is of no use as 
they aren't invoked when creating a sub interpreter.

One thing that does appear to work, although no idea of whether it is 
correct way to solve problem, is to duplicate the builtin/sys 
initialisation that occurs in Py_InitializeEx() function.

Attached diff shows nature of changes. Diff is bit messy as have left 
existing code in there but #ifdef'd out.

Maybe this will give someone who knows how overall interpreter 
initialisation is supposed to work a head start on coming up with proper 
fix. But then it could be totally wrong as well.

At least with change as is, mod_wsgi works for sub interpreters now. 
I'll do more work later on whether it is correct way to solve it.