libi3: change scalloc() signature to match calloc()

src/regex.c

@@ -25,7 +25,7 @@ struct regex *regex_new(const char *pattern) {
     const char *error;
     int errorcode, offset;
 
-    struct regex *re = scalloc(sizeof(struct regex));
+    struct regex *re = scalloc(1, sizeof(struct regex));
     re->pattern = sstrdup(pattern);
     int options = PCRE_UTF8;
 #ifdef PCRE_HAS_UCP