instead of llabs(), use std::abs()

Using std::abs() here causes a compilation error for ambiguous overloads of abs() since this template can be called on unsigned types. So the options are:

1. Keep it as-is
2. U locVal = -static_cast<U>(value); (refer to stackoverflow for details)
3. Some way to have special code for signed/unsigned types.

instead of llabs(), use std::abs()

Using std::abs() here causes a compilation error for ambiguous overloads of abs() since this template can be called on unsigned types. So the options are:

1. Keep it as-is
2. U locVal = -static_cast<U>(value); (refer to stackoverflow for details)
3. Some way to have special code for signed/unsigned types.

One solution would also be to use:

U locVal = (value < 0) ? -value : value;

Something involving std::is_signed_t<> and std::make_signed_t<> (to resolve the ambiguity) maybe?

Replaced with PR #4894