Shopify/ruby_memcheck: Use Valgrind memcheck on your native gem without going crazy

Valgrind's memcheck is a great tool to find and debug memory issues (e.g. memory leak, use-after-free, etc.). However, it doesn't work well on Ruby because Ruby does not free all of the memory it allocates during shutdown. This results in Valgrind reporting thousands (or more) false positives, making it very difficult for Valgrind to actually be useful. This gem solves the problem by using heuristics to filter out false positives.