Disable leak sanitizer

[shao-hua-li]

ASAN be default detects memory leaks, which are not actually undefined behaviors. https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer

We previously did not encounter this issue because csmith does not use any heap memory.

This PR disable leak sanitizer as I'm adding heap memory support to program generators.

[thetheodor]

Thanks for the PR. I think it would be even better to make it configurable instead of hardcoding the sanitizer environment parameters:

• the Sanitizer class should include a sanitizer_env_variables (or similarly named) attribute, that is initialized with some sane values and optionally can be overridden when creating a sanitizer object
• sanitizer_env_variables is used whenever check_for_sanitizer_errors is called.

Does this make sense?

[shao-hua-li]

Yes, it would be nice to allow users to setup the env

[shao-hua-li]

I have added a new sanitizer_env_variables para, which is set to the previous default value.

[thetheodor]

Thanks for the patch!