Add code for external symbol

tests/regression/test-simu/external_proc.c

+#include <stdio.h>
+#include "dataview-uniq.h"
+
+void orchestrator_RI_ExternalProc(asn1SccT_UInt32 *gnc_output, asn1SccT_UInt32 *gnc_input)
+{
+    *gnc_output = *gnc_input + 1;
+}