patch 7.4.1755

Problem:    When using getreg() on a non-existing register a NULL list is
            returned. (Bjorn Linse)
Solution:   Allocate an empty list. Add a test.

src/version.c

@@ -748,6 +748,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1755,
 /**/
     1754,
 /**/