[llvm] [FileCheck] Fix --enable-var-scope for numvars after reassignment (PR #157158)

[Thomas Preud'homme via llvm-commits]

RoboTux wrote:

I think the commit message should be rewritten because the real problem is that clearing of a local variable rely on the variable being in the global numeric table and thus a second clearning after a redefinition only works if the redefinition add it back to the global numeric variable table. Could you rephrase it accordingly? LGTM otherwise, thanks for your reply.

https://github.com/llvm/llvm-project/pull/157158