ip_utils: place sip_strerror in sip_utils

Change-Id: Id67818720dfa107be2f71b7de705a7117d147a74

src/ip_utils.cpp

@@ -49,13 +49,14 @@ WINSOCK_API_LINKAGE INT WSAAPI InetPtonA(INT Family, LPCSTR pStringBuf, PVOID pA
 
 namespace dhtnet {
 
+namespace sip_utils {
 std::string_view
 sip_strerror(pj_status_t code)
 {
     thread_local char err_msg[PJ_ERR_MSG_SIZE];
     return sip_utils::as_view(pj_strerror(code, err_msg, sizeof err_msg));
 }
-
+}
 
 std::string
 ip_utils::getHostname()