Fix unwind drop glue for if-then scopes cc `@est31` Fix #102317 Fix #99852 This PR fixes the drop glue for unwinding from a panic originated in a drop while breaking out for the else block in an `if-then` scope. MIR validation does not fail for the synchronous versions of the test program, because `StorageDead` statements are skipped over in the unwinding process. It is only becoming a problem when it is inside a generator where `StorageDead` must be kept around.