LifetimeDependenceDiagnostics: extend temp alloc to unreachable.
When a non-Escapable value depends on the address of a trivial value, we use a
special computeAddressableRange analysis to compute the trivial value's
scope. Extend that analysis to include unreachable paths.
Fixes this pattern:
inlineStorage.span.withUnsafeBytes
where inlineStorage is a trivial type defined in the user module. This
does not reproduce directly with InlineArray, but it is a problem for
user modules that have their own trivial wrapper around an InlineArray.
Fixes rdar://161630684 (Incorrect diagnostic: lifetime-dependent value escapes its scope)
(cherry picked from commit 98b7d5906cffa0cf7a481ba47a6acd746e388ac9)
