We were inlining the size and alignment, which was not correct.
This was the cause of a long-standing ASAN failure in some
library evolution tests.
Fixes <rdar://problem/24540778>.
Subclasses of resilient and generic classes now dynamically initialize
the vtable by copying the vtable from the superclass, and filling in
method overrides.
This means we no longer emit references to the base class's methods
statically, which allows the base class to add or remove an overload
resiliently without invalidating vtables of subclasses already
compiled.
Note that we still don't know how to slide subclass metadata when
the size of superclass metadata changes, so we can't resiliently
add or remove vtable entries yet.
