Umbrella header 'TrueTime.h' not found

Hey. I got this weird issues testing the demo iOS application

Issue in Script:
```
framework module TrueTime {
umbrella header "TrueTime.h" // *Umbrella header 'TrueTime.h' not found*

export *
module * { export * }
}

module TrueTime.__Swift {
exclude header "TrueTime-Swift.h"
}

```

Compiler error:
```
umbrella header 'TrueTime.h' not found
umbrella header "TrueTime.h"
^
:0: error: could not build Objective-C module 'TrueTime'

```

Does anyone know how to get rid of the error?

Start with the module script in the demo iOS application, focusing on the TrueTime.h umbrella header and the excluded TrueTime-Swift.h header. Check how those headers are supplied to the TrueTime module, then rebuild the demo and confirm that the Objective-C module compiles without the umbrella-header error.

Written by the indexing model from the issue text.