Disable warning C4200 on VC++

- This warning is about using zero-sized arrays in structs (aka flexible
  member arrays). It's standard-enough for our purposes, so don't warn
  about it, since neither GCC nor Clang do.

src/doomtype.h

@@ -34,6 +34,10 @@
 // source files, so we can't use it. So define PATH_MAX to be what MAX_PATH
 // currently is:
 #define PATH_MAX 260
+
+// Disable warning about using unsized arrays in structs. It supports it just
+// fine, and so do Clang and GCC, but the latter two don't warn about it.
+#pragma warning(disable:4200)
 #endif
 
 #include <limits.h>

src/textures/textures.h

@@ -107,8 +107,6 @@ struct FDoorAnimation
 	FName CloseSound;
 };
 
-
-
 // Patches.
 // A patch holds one or more columns.
 // Patches are used for sprites and all masked pictures, and we compose