patch 7.4.1872

Problem:    Still build problem with old version of Perl.
Solution:   Also define SvREFCNT_inc_void_NN if needed. (Ken Takata)

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1872,
 /**/
     1871,
 /**/