[php-src] PR #23967: ext/bcmath: Clear the sign of BcMath\Number results that truncate to zero

Pull Request: https://github.com/php/php-src/pull/23967 Author: iliaal Several BcMath\Number operations kept the operand's negative sign when the result truncated to zero at the requested scale: the bc_divide() fast paths for a divisor of 1, -1 or a power of ten, bc_raise() with a positive exponent, and the add/sub/mul helpers. (new BcMath\Number('-0.001'))->div(1, 0) then compares less than 0, is not equal to 0, and makes sqrt() throw. String output already drops the sign of a zero, so the procedural functions are not affected.