FCS: fix clang warnings
Fix clang warnings in FCS code after LCG update in !72568 (merged).
Use std::abs instead of fabs for integer types. Also use other math functions from the std namespace instead.
Fix clang warnings in FCS code after LCG update in !72568 (merged).
Use std::abs instead of fabs for integer types. Also use other math functions from the std namespace instead.