Issue Description:

The Swift importer will blindly try to create an N-element tuple for C arrays of size N. This quickly becomes ridiculous even for fairly small arrays like 16 or 32. It becomes downright pathological from a visual standpoint as the array goes past 128 or so, and at arrays past 1024 starts exhibiting semi-exponential behavior in time; generating the Swift interface for a header containing a 65536-element array takes almost 5 full minutes on a MBP. The importer should refuse to handle such large arrays.

Steps To Reproduce:

1. Create an Objective-C project.
2. In any header, declare a huge array; for example, “static char myLudicrousArray[65536];”
3. Attempt to view the generated Swift interface for the header, or import the header in a Swift bridging header and try to build any Swift code.

Results:
The interface takes quite a long time to generate.

Regression:
This has always been the case for as far back as the “generate N-element tuples for N-element arrays” logic has existed.

Notes:
Arrays of such excessive size are not necessarily common, but they do appear in practice. Pending a better way to import C arrays in general, especially large ones, Swift should better own its inability to handle them effectively.