Ignore check prefixes at the ends of words

[tlively]

Ignore check prefixes that are actually the ends of longer words. For example, a
line containing "NO-CHECK:" should not be interpreted as containing a "CHECK:"
directive. A check prefix is considered to be the end of a longer word if there
is a character before it on the same line and that character is alphanumeric,
"_", or "-", just like in upstream FileCheck.

[tlively]

Hi! Thanks for putting this package together. We're about to start using it for running some of our tests for https://github.com/webassembly/binaryen. I don't think we'll need many of the more advanced FileCheck features that aren't yet implemented here, but I've found the capability in this PR useful in upstream LLVM. The other very useful feature I expect to want eventually is the --check-prefixes=<prefix1>,<prefix2> to enable multiple prefixes at once. I'll probably make another PR adding that functionality when I need it.

[stanislaw]

Hi! Thanks for putting this package together. We're about to start using it for running some of our tests for https://github.com/webassembly/binaryen. I don't think we'll need many of the more advanced FileCheck features that aren't yet implemented here, but I've found the capability in this PR useful in upstream LLVM. The other very useful feature I expect to want eventually is the --check-prefixes=<prefix1>,<prefix2> to enable multiple prefixes at once. I'll probably make another PR adding that functionality when I need it.

We are glad that you find this package useful. Thank you for your contributions. The --check-prefixes was one of the next items on my todo list - I would be happy to accept a PR.