patch 9.0.0052: "zG" may throw an error if invalid character follows

Problem:    "zG" may throw an error if invalid character follows.
Solution:   Pass the word length to valid_spell_word(). (Ken Takata,
            closes #10737)

src/version.c

@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    52,
 /**/
     51,
 /**/