When outlining a destroy operation, we form direct calls to the deinit
of noncopyable types. For generic types, this was always calling into
unspecialized generics, which is... deeply unfortunate.
Look for a specialized deinit and call that instead. This eliminates a
compiler assertion in Embedded Swift, and should improve performance
with noncopyable generics elsewhere.
Fixes rdar://159054138 and #72627 / rdar://157131184.
