Fix compiler warning.

NULL is NOT 0 (zero).

src/lib/edit.c

@@ -255,13 +255,36 @@ bool duration_to_utime(char *str, utime_t *value)
    double val, total = 0.0;
    char mod_str[20];
    char num_str[50];
+
    /*
     * The "n" = mins and months appears before minutes so that m maps to months.
     */
-   static const char *mod[] = {"n", "seconds", "months", "minutes", "mins",
-                  "hours", "days", "weeks",   "quarters",   "years", NULL};
-   static const int32_t mult[] = {60,   1, 60*60*24*30, 60, 60,
-                  3600, 3600*24, 3600*24*7, 3600*24*91, 3600*24*365};
+   static const char *mod[] = {
+      "n",
+      "seconds",
+      "months",
+      "minutes",
+      "mins",
+      "hours",
+      "days",
+      "weeks",
+      "quarters",
+      "years",
+      (char *)NULL
+   };
+   static const int32_t mult[] = {
+      60,
+      1,
+      3600 * 24 * 30,
+      60,
+      60,
+      3600,
+      3600 * 24,
+      3600 * 24 * 7,
+      3600 * 24 * 91,
+      3600 * 24 * 365,
+      0
+   };
 
    while (*str) {
       if (!get_modifier(str, num_str, sizeof(num_str), mod_str, sizeof(mod_str))) {