Update gis.h

Replace SVN keyword $Revision$ with generic GRASS_VERSION_STRING

include/gis.h

@@ -27,6 +27,7 @@
 /* Grass and local include files */
 #include <grass/config.h>
 #include <grass/datetime.h>
+#include <grass/version.h>
 
 /*=========================== Constants/Defines ============================*/
 
@@ -38,7 +39,7 @@
 static const char *GRASS_copyright __attribute__ ((unused))
     = "GRASS GNU GPL licensed Software";
 
-#define GIS_H_VERSION "$Revision$"
+#define GIS_H_VERSION "GRASS_VERSION_STRING"
 #define GIS_H_DATE    "$Date$"
 
 #define G_gisinit(pgm) G__gisinit(GIS_H_VERSION, (pgm))