[llvm] [FileCheck] Limit quadratic partial-match search behavior (PR #147833)

[Thomas Preud'homme via llvm-commits]

RoboTux wrote:

You should use %ProtectFileCheckOutput on the first FileCheck invocation I believe, similar to what is done in llvm/test/FileCheck/bad-char.txt for instance.

https://github.com/llvm/llvm-project/pull/147833