Some tests work very slow on Clang in Debug mode

[p-senichenkov]

There's a test named "LightDatasetConsistentHash", which takes a while with all FD algorithms, but becames inadequately slow with FDep algo on LLVM (both Linux and macOS, LLVM and Apple Clang) in Debug mode without sanitizers. One test runs about an hour. 😱

Sanitizers somehow fix it, but run time is still no so good (about 10 minutes):

On Linux with GCC in Debug mode it takes about 5 minutes:

[p-senichenkov]

This test takes 5 minutes on Clang in Release:

and 20 seconds on GCC in Release: