Fix a few more cases of ArrayRef problems.

[bob-wilson]

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

Resolves SR-NNNN.

This is another problem (like 5356cc3) exposed by building with a newer
version of Clang. Construct a temporary SmallVector when needed to create
an ArrayRef.

[bob-wilson]

@swift-ci please smoke test

[jrose-apple]

This one I would expect to work correctly as is. How did you find the issue?

[bob-wilson]

I just ran it in the debugger and it crashed while iterating over the array. Since it looked like the other problems, I just blindly tried the same fix.

[jrose-apple]

Hm. I'm looking at the AST dump and it looks like it should be okay. It's the moral equivalent of

extern int &fallback();
int p = getValue();
const int &r = p > 0 ? p : fallback();
use(r);

and I'm pretty sure Clang reusing the stack space for p would be a bug.

[jrose-apple]

(Ignore the lifetime extension rules for temporaries here. p itself is not a temporary.)