[Sema] Silence an inconsistent availability error for the stdlib
[Sema] Silence an inconsistent availability error for the stdlib

Don't raise the error availability_decl_more_than_enclosing in the
context is unavailable and if read in a swiftinterface file. This error
was present in the stdlib in 5.3 without side effects so we still want
to accept it.

roambotics/swift,jmgc/swift,rudkx/swift,JGiola/swift,JGiola/swift,parkera/swift,gregomni/swift,ahoppen/swift,parkera/swift,tkremenek/swift,hooman/swift,apple/swift,JGiola/swift,benlangmuir/swift,xwu/swift,gregomni/swift,tkremenek/swift,apple/swift,gregomni/swift,jmgc/swift,jmgc/swift,xwu/swift,benlangmuir/swift,xwu/swift,hooman/swift,benlangmuir/swift,xwu/swift,hooman/swift,glessard/swift,atrick/swift,xwu/swift,roambotics/swift,parkera/swift,atrick/swift,hooman/swift,gregomni/swift,ahoppen/swift,benlangmuir/swift,rudkx/swift,xwu/swift,atrick/swift,roambotics/swift,jmgc/swift,rudkx/swift,JGiola/swift,JGiola/swift,ahoppen/swift,jmgc/swift,atrick/swift,benlangmuir/swift,roambotics/swift,jmgc/swift,apple/swift,rudkx/swift,tkremenek/swift,hooman/swift,hooman/swift,parkera/swift,apple/swift,glessard/swift,glessard/swift,rudkx/swift,tkremenek/swift,benlangmuir/swift,rudkx/swift,tkremenek/swift,atrick/swift,atrick/swift,gregomni/swift,ahoppen/swift,xwu/swift,tkremenek/swift,parkera/swift,ahoppen/swift,tkremenek/swift,gregomni/swift,parkera/swift,roambotics/swift,glessard/swift,glessard/swift,jmgc/swift,apple/swift,parkera/swift,ahoppen/swift,roambotics/swift,parkera/swift,JGiola/swift,glessard/swift,hooman/swift,apple/swift