Fix libpar2 patch check in NZBGet 9.1

Unfortunately I didn't test my earlier update fully, only ran it on my dev machine. NZBGet 9.1 includes two patches for libpar2 that they suggest you run, and the configure now checks for
 them.

Not sure whether the best thing to do is disable the check (which is what this update does), or update the libpar2 formula. Upstream libpar2 seems to be gone, so it'd just be patches in the libpar2 formula.

If the best approach is to disable the check, please accept both my apologies and this pull request. Otherwise, let me know and I'll add the patches to libpar2.

Sorry for the earlier mistake!

Thanks, Sean.