patch 7.4.1756

Problem:    "dll" options are not expanded.
Solution:   Expand environment variables. (Ozaki Kiichi)

src/version.c

@@ -748,6 +748,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1756,
 /**/
     1755,
 /**/