[stdlib] Speed up ObjectIdentifier-keyed dictionaries
[stdlib] Speed up ObjectIdentifier-keyed dictionaries

ObjectIdentifier is used relatively frequently as the Key type for dictionaries, so it makes sense for it to implement single-shot hashing. This will lead to a measurable speedup in lookup/insertion performance.

rdar://88339458

ahoppen/swift,gregomni/swift,benlangmuir/swift,gregomni/swift,ahoppen/swift,JGiola/swift,rudkx/swift,gregomni/swift,apple/swift,atrick/swift,atrick/swift,JGiola/swift,gregomni/swift,benlangmuir/swift,gregomni/swift,glessard/swift,atrick/swift,rudkx/swift,roambotics/swift,JGiola/swift,ahoppen/swift,roambotics/swift,rudkx/swift,rudkx/swift,benlangmuir/swift,ahoppen/swift,JGiola/swift,benlangmuir/swift,roambotics/swift,benlangmuir/swift,benlangmuir/swift,glessard/swift,gregomni/swift,glessard/swift,atrick/swift,roambotics/swift,ahoppen/swift,JGiola/swift,roambotics/swift,apple/swift,glessard/swift,apple/swift,atrick/swift,rudkx/swift,rudkx/swift,ahoppen/swift,apple/swift,atrick/swift,glessard/swift,glessard/swift,apple/swift,roambotics/swift,apple/swift,JGiola/swift