svchost: Added base implementation of svchost (1/27)

[Roy Shea]

Hello Juan,

Thank you for the code review!  A quick clarification about HeapFree:

> Some judicious use of goto could reduce code for all your error paths.
> Remember that HeapFree of a NULL pointer is allowed.

The docs for HeapFree state "If this pointer is NULL, the behavior is
undefined."  So in practice the undefined behavior is benign?

Peace,
-Roy