Static: fixed potential undefined behavior in memcpy().
According to the C standard, pointer arguments passed to memcpy() calls shall
still have valid values.  NULL is considered as invalid.
Found with GCC Static Analyzer.
@@ -76,7 +76,7 @@ nxt_http_static_handler(nxt_task_t *task, nxt_http_request_t *r,
nxt_str_set(&extension, ".html");
} else {
- nxt_str_null(&index);
+ nxt_str_set(&index, "");
nxt_str_null(&extension);
}
