patch 7.4.1783

Problem:    The old regexp engine doesn't handle character classes correctly.
            (Manuel Ortega)
Solution:   Use regmbc() instead of regc().  Add a test.

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1783,
 /**/
     1782,
 /**/