Some more fixes for errors MSVC2003 noticed

Now I've got the entire project building with MSVC2003, _and_ I can
compare its ASM with Devilution's disassembler tool.

src/Draw.cpp

@@ -1,6 +1,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <string.h>
 
 #ifdef WINDOWS
 #define RECT WINRECT

src/Main.cpp

@@ -2,6 +2,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <string.h>
 
 #include <SDL.h>

src/Organya.cpp

@@ -2,6 +2,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <string.h>
 
 #include <SDL_rwops.h>