net/gcoap: move macros to implementation file

sys/include/net/gcoap.h

@@ -252,30 +252,6 @@ extern "C" {
 #define GCOAP_PDU_BUF_SIZE      (128)
 #endif
 
-/**
- * @brief   Reduce payload length by this value for a request created with
- *          gcoap_req_init()
- *
- * Accommodates writing Content-Format option in gcoap_finish()
- */
-#define GCOAP_REQ_OPTIONS_BUF   (4)
-
-/**
- * @brief   Reduce payload length by this value for a respons created with
- *          gcoap_resp_init()
- *
- * Accommodates writing Content-Format option in gcoap_finish()
- */
-#define GCOAP_RESP_OPTIONS_BUF  (4)
-
-/**
- * @brief   Reduce payload length by this value for an observe notification
- *          created with gcoap_obs_init()
- *
- * Accommodates writing Content-Format option in gcoap_finish()
- */
-#define GCOAP_OBS_OPTIONS_BUF   (4)
-
 /**
  * @brief   Maximum number of requests awaiting a response
  */

sys/net/application_layer/gcoap/gcoap.c

@@ -38,6 +38,15 @@
 #define GCOAP_RESOURCE_WRONG_METHOD -1
 #define GCOAP_RESOURCE_NO_PATH -2
 
+/*
+ * Reduce payload length by this value for a request created with
+ * gcoap_req_init(), gcoap_resp_init(), and gcoap_obs_init(), respectively.
+ * Accommodates writing Content-Format option in gcoap_finish().
+ */
+#define GCOAP_REQ_OPTIONS_BUF   (4)
+#define GCOAP_RESP_OPTIONS_BUF  (4)
+#define GCOAP_OBS_OPTIONS_BUF   (4)
+
 /* Internal functions */
 static void *_event_loop(void *arg);
 static void _listen(sock_udp_t *sock);