use separated libosmo-mgcp-client, apply rename to mgcp_client_*

After osmo-mgw changes I8e0b2d2a399b77086a36606f5e427271c6242df1 and
I99f7faab637cfcc22ece64a1dbcbe590f2042187, apply linking of new
libosmo-mgcp-client and renames to drop the "gw" from mgcp_client_*.

Also rename the gsm_network.mgcpgw to mgw, to indicate that the MGCP client is
used to contact the MGW (Media Gateway).

Depends: I8e0b2d2a399b77086a36606f5e427271c6242df1 (osmo-mgw)
         I99f7faab637cfcc22ece64a1dbcbe590f2042187 (osmo-mgw)
Change-Id: I093ad02ca0e532f659447c785e09678b3e6f220d
diff --git a/src/libmsc/gsm_04_08.c b/src/libmsc/gsm_04_08.c
index 2ef0b30..84f52c6 100644
--- a/src/libmsc/gsm_04_08.c
+++ b/src/libmsc/gsm_04_08.c
@@ -2667,7 +2667,7 @@
 	 * (0 if unknown) */
 	msg_type = GSM_TCHF_FRAME;
 
-	uint32_t addr = mgcpgw_client_remote_addr_n(net->mgcpgw.client);
+	uint32_t addr = mgcp_client_remote_addr_n(net->mgw.client);
 	uint16_t port = trans->conn->rtp.port_cn;
 
 	/* FIXME: This has to be set to some meaningful value,