[boost] [concept_check][ublas] Fixing deprecated copy warnings

Hi, There are two PR that fix deprecated copy warnings for GCC and Clang: * https://github.com/boostorg/concept_check/pull/35 * https://github.com/boostorg/ublas/pull/153 Please review those. They make the intent explicit and the code becomes more portable. Trivial sample that causes the warning https://godbolt.org/z/YaPvGfedv -- Best regards, Antony Polukhin