Previously windows build could only use yasm because some procedural items such
as proc_start were not supported by nasm. This adds a few macros and fixes so
nasm can be used to build on windows.
Change-Id: Ia05dc3ff482f33b0f915bb1be3c7df5e4a753b3a
Signed-off-by: Greg Tucker <greg.b.tucker@intel.com>