[llvm] [TableGen] Handle Windows line endings in x86-fold-tables.td test (PR #112997)

[Daniel Paoliello via llvm-commits]

dpaoliello wrote:

Given that we've seen this issue on AIX before, and there wasn't a good place to only use the internal shell for a single test, I decided to modify lit to always use the internal shell on AIX: https://github.com/llvm/llvm-project/pull/113355

https://github.com/llvm/llvm-project/pull/112997