nmake scripts missing include ../ext path

All 0.2.4+ nmake makefiles need to be updated to match the change that split off external code to the ../ext directory. In particular, since all of them are used in the main codebase via #include "..." directives, ext needs to be in the include path.

The fix is easy, just append /I ..\ext to every CFLAGS.

PS: an even cleaner way would be to split off an INCLUDES variable to hold the include paths. Maybe even use some $() magic to tack on the /I part after-the-fact.

Trac:
Username: ultramage