Tests importing AppKit have a tendency to be flaky if they share a
module cache with other builds using a different set of framework search
flags. Make sure they use a local cache to avoid picking incompatible
cached modules.
Alternatively, we could align all builds using the same cache to have
exactly the same framework search paths or enable explicit module
builds. I picked the module cache as it's the most reliable solution in
the short and long term.
The 5 tests below import AppKit and have been known to be flaky.
Adapting them to use a custom cache with require more care. For now,
let's use them as control group to validate that the fix works. If these
5 fail without the fixed ones, we should extend the same corresponding
fix to them.
- Interpreter/SDK/GLKit.swift
- Interpreter/SDK/cf_extensions.swift
- Interpreter/SDK/cf_type_bridging.swift
- Interpreter/SDK/mapkit_header_static.swift
- Interpreter/SDK/objc_ns_enum.swift
rdar://142296731
This involved adding a new substitution called %api_diff_data_dir that when
building against a host toolchain, looks in the host toolchain (next to swiftc)
rather than in the resource dir. The reason why I need to do this is this allows
me to perform a stdlib stage2 build without needing to build swift itself.
The only interesting changes here are that I had to add %api_diff_data_dir to
a bunch of normal/expected tests and also add %api_diff_data_dir's length to the
offsets in rdar31892850.swift.
