BaseTools: use stdint.h for GCC ProcessorBind.h typedefs

BaseTools: use stdint.h for GCC ProcessorBind.h typedefs

The AArch64 definitions of UINT64/INT64 differ from the X64 ones.
Since this is on the tool side, doing like X64 and picking the
definitions from stdint.h feels like a better idea than hardcoding
them. So copy the pattern from X64/ProcessorBind.h.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>