remove @# from GRASS_VERSION_STRING (#528)

include/version.h.in

@@ -1,4 +1,4 @@
-#define GRASS_VERSION_STRING   "@(#) @GRASS_VERSION_NUMBER@ (@GRASS_VERSION_DATE@)"
+#define GRASS_VERSION_STRING   "@GRASS_VERSION_NUMBER@ (@GRASS_VERSION_DATE@)"
 #define GRASS_VERSION_MAJOR    @GRASS_VERSION_MAJOR@
 #define GRASS_VERSION_MINOR    @GRASS_VERSION_MINOR@
 #define GRASS_VERSION_RELEASE  @GRASS_VERSION_RELEASE@