- Fix errors/warnings from MinGW 4.5.0 (tdm-1).

- Disable the missing field initializers warnings that -Wextra produces from GCC.

SVN r3173 (trunk)

src/p_buildmap.cpp

@@ -767,8 +767,8 @@ static void CreateStartSpot (fixed_t *pos, FMapThing *start)
 		0, (LittleLong(pos[0])<<12), ((-LittleLong(pos[1]))<<12), 0,// tid, x, y, z
 		short(Scale ((2048-angle)&2047, 360, 2048)), 1,	// angle, type
 		0, 0,							// Skillfilter, Classfilter
-		7|MTF_SINGLE|224,										// flags
-		0, {NULL}, NULL 			// special is 0, args and Conversation are NULL
+		7|MTF_SINGLE|224,				// flags
+		0, {0}, 0 						// special is 0, args and Conversation are 0
 	};
 
 	*start = mt;