gprs_gsup_client*: remove the gprs_ prefix

Make sure everything is named gsup_client_ / GSUP_CLIENT_.

Rename static gsup_client_send() to client_send() to avoid clash with public
gprs_gsup_client_send() being renamed to gsup_client_send().

This is in preparation for moving gsup to libcommon, which is in turn
preparation for libvlr. libvlr and osmo-sgsn will use the same GSUP client
code. A number of patches will follow up on this, also for the the OAP client.

Related: OS#1592
Change-Id: I57433973b1c4f6cc1e12e7b1c96b5f719f418b51
diff --git a/openbsc/tests/sgsn/Makefile.am b/openbsc/tests/sgsn/Makefile.am
index 9ee5455..c5d90f6 100644
--- a/openbsc/tests/sgsn/Makefile.am
+++ b/openbsc/tests/sgsn/Makefile.am
@@ -36,7 +36,7 @@
 	-Wl,--wrap=sgsn_update_subscriber_data \
 	-Wl,--wrap=gprs_subscr_request_update_location \
 	-Wl,--wrap=gprs_subscr_request_auth_info \
-	-Wl,--wrap=gprs_gsup_client_send \
+	-Wl,--wrap=gsup_client_send \
 	$(NULL)
 
 sgsn_test_LDADD = \