swift234

Targeted fix for pulling in Hashable conformance for Set and Dictionary when a nil literal is bridged

When bridging values via the ObjectiveCBridgeable protocol,
SILGen has to look up conformances directly, behind the
type checker's back.

To make sure the ObjectiveCBridgeable conformance is forced,
Sema calls useObjectiveCBridgeableConformances() in the right
places.

However, another conformance we may also need when bridging
is the Hashable conformance for a Set or Dictionary's key type.

Make sure we force these too, because otherwise when bridging
a nil literal nothing needs them in Sema.

Fixes <rdar://problem/27470505>.