Make vboot_reference build in MSVC command line environment.

This is a mostly NOOP change which modifies the source code
to compile cleanly in the MSVC command line build
environment.

A new makefile is introduced (msc/nmakefile) along with a
README.txt in the same directory explaining how to build
the code in the DOS window. As of this submission the build
is running in a 32 bit environment, the intention is to use
the same makefile for 64 bit builds in the future.

Enabling high compilation warnings level allowed to
identify a couple of bugs in the code which are being fixed.

Not all sources are being compiled in the MSVC environment,
only those in firmware/ and most of those in test/
subdirectories. The benchmark calculations require porting
of the timer facilities and are being postponed.

TEST

Built in DOS and linux environments. Ran unit tests in
linux environment.

Review URL: http://codereview.chromium.org/2809037

firmware/lib/include/vboot_struct.h

@@ -11,9 +11,7 @@
 
 #include "sysincludes.h"
 
-#ifdef _MSC_VER
-#pragma pack(push, 1) /* Support packing for MSVC. */
-#endif
+__pragma(pack(push, 1)) /* Support packing for MSVC. */
 
 /* Public key data */
 typedef struct VbPublicKey {
@@ -133,8 +131,6 @@ typedef struct VbKernelPreambleHeader {
 
 #define EXPECTED_VBKERNELPREAMBLEHEADER_SIZE 96
 
-#ifdef _MSC_VER
-#pragma pack(pop) /* Support packing for MSVC. */
-#endif
+__pragma(pack(pop)) /* Support packing for MSVC. */
 
 #endif  /* VBOOT_REFERENCE_VBOOT_STRUCT_H_ */