updated for version 7.3.815

Problem:    Building with Cygwin and Ruby doesn't work.
Solution:   Copy some things from the MingW build file. (Ken Takata)

src/version.c

@@ -725,6 +725,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    815,
 /**/
     814,
 /**/