stdlib: Avoid condfails resulting from typed throws adoption.
The standard library's swiftinterface must temporarily remain buildable when
`$TypedThrows` evaluates to false since there are still supported Swift 5.11
compilers that did not have the feature enabled by default. Declarations using
typed throws in their signatures are guarded in printed swiftinterface files
with `#if $TypedThrows` and therefore `@inlinable` code that uses those
declarations must also be conditionalized on `$TypedThrows`.
