LLVMFuzzerInitialize doesn't not error on Non Zero

[zz85]

Problem:

https://github.com/llvm-mirror/compiler-rt/blob/master/lib/fuzzer/FuzzerInterface.h#L47 says mentions LLVMFuzzerInitialize() should return 0.

However, testing LLVMFuzzerInitialize() shows that libfuzzer does not error when -1 is returned. This can be dangerous if we are assuming tests to fail if a function is GUARDed in LLVMFuzzerInitialize.

Proposed Solution:

Move non-expensive initialization calls to LLVMFuzzerTestOneInput(), or add sanity checks in the main fuzz test function.

[jmayclin]

Should be investigated a bit more. Hopefully LLVM has fixed this on more recent versions.

We should confirm that LLVMFuzzerInitialize reliably fails if we return a -1. If so, we can close this issue.