fix: static analysis under-reports Swift value types

[kcsiegal]

I noticed while using Reaper in a production app that the SDK was reporting a surprisingly large set of Swift structs and enums at runtime that the static analysis was not detecting in the app bundle.

The underlying cause is an incorrectly bounded loop in validSwiftTypesForReaper when iterating over the __swift5_types section. The section is an array of 4-byte relative pointers and the loop correctly strides by 4, but it bounds itself at swiftTypesData.length / 8, so the second half of the section is never visited. Updating numTypes to swiftTypesData.length / 4 surfaces the missing value types.