swift

f649ed0e - test: Stop disabling availability checking in typeref_lowering.swift.

test: Stop disabling availability checking in typeref_lowering.swift. The test compiles TypeLowering.swift with a Swift 5.2 deployment target and relies on -disable-availability-checking to allow the AFD types, which store an InlineArray. Mark those types @available(SwiftStdlib 6.2, *) instead, so the deployment target the test pins keeps its meaning.