CLEANUP: stconn: rename final state manipulation functions from cs_* to sc_*

This applies the following renaming. It's a bit large but pretty
mechanical:

cs_state -> sc_state  (enum)

cs_alloc_ibuf() -> sc_alloc_ibuf()
cs_is_conn_error() -> sc_is_conn_error()
cs_opposite() -> sc_opposite()
cs_report_error() -> sc_report_error()
cs_set_state() -> sc_set_state()
cs_state_bit() -> sc_state_bit()
cs_state_in() -> sc_state_in()
cs_state_str() -> sc_state_str()
diff --git a/src/dns.c b/src/dns.c
index 749387e..bab396b 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -471,7 +471,7 @@
 	/* if the connection is not established, inform the stream that we want
 	 * to be notified whenever the connection completes.
 	 */
-	if (cs_opposite(cs)->state < SC_ST_EST) {
+	if (sc_opposite(cs)->state < SC_ST_EST) {
 		applet_need_more_data(appctx);
 		se_need_remote_conn(appctx->sedesc);
 		applet_have_more_data(appctx);
@@ -506,7 +506,7 @@
 	 * the message so that we can take our reference there if we have to
 	 * stop before the end (ret=0).
 	 */
-	if (cs_opposite(cs)->state == SC_ST_EST) {
+	if (sc_opposite(cs)->state == SC_ST_EST) {
 		/* we were already there, adjust the offset to be relative to
 		 * the buffer's head and remove us from the counter.
 		 */