patch 7.4.1922

Problem:    Ruby 2.4.0 unifies Fixnum and Bignum into Integer.
Solution:   Use rb_cInteger. (Weiong Mao)

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1922,
 /**/
     1921,
 /**/