GCC compatibility for honggfuzz

Hello,

I've been trying to integrate rules_fuzzing + honggfuzz into our bazel build system with a custom GCC toolchain. I'm a little confused about whether rules_fuzzing is expected to support GCC natively in this case. There seems to be past issues and [pull requests](https://github.com/bazel-contrib/rules_fuzzing/pull/177) indicating there is GCC support, but I also see clang-specific flags like -mllvm in the build options. Would you mind clarifying if this is supported, and in case the answer is yes, what's the intended way for this integration to be used?

Thanks!