nulstr-util: Declare NULSTR_FOREACH() iterator inline

src/libsystemd/sd-device/device-private.c

@@ -559,7 +559,6 @@ static int device_update_properties_bufs(sd_device *device) {
                 return -ENOMEM;
 
         size_t i = 0;
-        char *p;
         NULSTR_FOREACH(p, buf_nulstr)
                 buf_strv[i++] = p;
         assert(i == num);

src/libsystemd/sd-device/test-sd-device.c

@@ -534,7 +534,7 @@ TEST(sd_device_new_from_nulstr) {
 
         _cleanup_(sd_device_unrefp) sd_device *device = NULL, *from_nulstr = NULL;
         _cleanup_free_ char *nulstr_copy = NULL;
-        const char *devlink, *nulstr;
+        const char *nulstr;
         size_t len;
 
         assert_se(sd_device_new_from_syspath(&device, "/sys/class/net/lo") >= 0);