(svn r2542) -Add: [GPMI] Added GPMI (http://sourceforge.net/projects/libgpmi/)

support to OpenTTD in preperation of AIScripts (long term). It is OFF 
  by default. Add GPMI:=1 to Makefile.config to enable.

debug.h

@@ -15,6 +15,9 @@
 	extern int _debug_spritecache_level;
 	extern int _debug_oldloader_level;
 	extern int _debug_pbs_level;
+#ifdef GPMI
+	extern int _debug_gpmi_level;
+#endif /* GPMI */
 	extern int _debug_npf_level;
 #endif
 
@@ -23,4 +26,8 @@ void CDECL debug(const char *s, ...);
 void SetDebugString(const char *s);
 const char *GetDebugString(void);
 
+#ifdef GPMI
+void gpmi_debug_openttd(int level, char *s);
+#endif /* GPMI */
+
 #endif