Rustc runs out of memory when dealing with extremely large array literals in macros

[ahicks92]

Playground link: https://is.gd/WsYvhb

This was originally a typo having to do with using a screen reader, which doesn't read exclamations in positions which it decides aren't the ends of sentences well with my currently configured settings. I first observed it locally with 0.10 i686-pc-windows-gnu.

Expected behavior with that version and triple appears to be an error message about the array constant being too large for the current architecture. Specifically, per IRC:

error: the type `[u8; 18446744073709550615]` is too big for the current architecture 

Modifying the code in the very obvious manner to fix it makes it work fine.

[Aatch]

Duplicate of #30083. The "capacity overflow" is from trying to create the massive vector to pass to LLVM.