test: triplicate a test

[compnerd]

The runtime can be out of date and cause spurious failures. Copy the
test over thrice to deal with that. Requested by Mark Lacey.

Replace this paragraph with a description of your changes and rationale. Provide links to external references/discussions if appropriate.

Resolves SR-NNNN.

[compnerd]

CC: @rudkx @jrose-apple

Not sure if Jordan has strong opinions on having three copies of the test (I think that it is probably better to rely on developers to do clean builds than have three copies of the test).

[compnerd]

@swift-ci please test

[jrose-apple]

No, I'm with Mark, since there's plenty of times when I configure to build the iOS stdlib but haven't built it yet. (And left a comment to that effect back in December.) You need to add the REQUIRES check to actually make this useful, though.

[compnerd]

Actually, looking at this again, I had tried to make it not depend on the stdlib ... note that it uses -parse-stdlib so it shouldn't be dependent on the stdlib, no?

[compnerd]

@swift-ci please test

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 3f1c720ba36a08ffb92c0b3cac5bd4f9e51897c4

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 3f1c720ba36a08ffb92c0b3cac5bd4f9e51897c4

[jrose-apple]

As I said on #13225, it's probably still using the stdlib because you're importing types from C. I don't think the importer is set up to avoid looking things up in -parse-stdlib mode, and it's not really worth your time to do that.

[compnerd]

@swift-ci please test and merge