Provide handle_nr_srs_measurements() in 4G

4G/5G FAPI code is located in the same file. Since 5G code calls 5G
specific functions, these functions need to be defined in 4G.

The solution would be to separate the FAPI changes into 4G and 5G.

executables/lte-softmodem.c

@@ -193,6 +193,16 @@ bool nr_pdcp_data_req_drb(protocol_ctxt_t *ctxt_pP,
   abort();
 }
 
+/* hack: nfapi code is common for 4G/5G, so some function calls are hardcoded.
+ * Provide body for 5G function not used in 4G code */
+void handle_nr_srs_measurements(const module_id_t module_id,
+                                const frame_t frame,
+                                const sub_frame_t slot,
+                                nfapi_nr_srs_indication_pdu_t *srs_ind)
+{
+  return;
+}
+
 /* forward declarations */
 void set_default_frame_parms(LTE_DL_FRAME_PARMS *frame_parms[MAX_NUM_CCs]);