patch 7.4.1976
Problem:    Number variables are not 64 bits while they could be.
Solution:   Add the num64 feature. (Ken Takata)
diff --git a/src/option.c b/src/option.c
index 80bd867..47bbe73 100644
--- a/src/option.c
+++ b/src/option.c
@@ -4179,7 +4179,7 @@
     int		afterchar;	    /* character just after option name */
     int		len;
     int		i;
-    long	value;
+    varnumber_T	value;
     int		key;
     long_u	flags;		    /* flags for current option */
     char_u	*varp = NULL;	    /* pointer to variable for current option */
@@ -9102,7 +9102,7 @@
 	if ((int *)varp == &curbuf->b_changed)
 	    *numval = curbufIsChanged();
 	else
-	    *numval = *(int *)varp;
+	    *numval = (long) *(varnumber_T *)varp;
     }
     return 1;
 }