BaseTools/CommonLib: get rid of 'native' type string parsing routines

BaseTools/CommonLib: get rid of 'native' type string parsing routines

Parsing a string into an integer variable of the native word size
is not defined for the BaseTools, since the same tools may be used
to build firmware for different targets with different native word
sizes.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>