mgw, mgcp-li: Handle X-Osmux param name as case insensitive

RFC3435 states most text (except SDP) must be handled as case
insensitive.

Related: OS#4001
Change-Id: Iac073f1db46569b46eddeaecc9934a2986bd50f1
diff --git a/src/libosmo-mgcp/mgcp_msg.c b/src/libosmo-mgcp/mgcp_msg.c
index a31bff4..59e0e91 100644
--- a/src/libosmo-mgcp/mgcp_msg.c
+++ b/src/libosmo-mgcp/mgcp_msg.c
@@ -360,12 +360,12 @@
 	int osmux_cid;
 
 
-	if (strstr(line + 2, "Osmux: *")) {
+	if (strcasecmp(line + 2, "Osmux: *") == 0) {
 		LOGP(DLMGCP, LOGL_DEBUG, "Parsed wilcard Osmux CID\n");
 		return -1;
 	}
 
-	if (sscanf(line + 2, "Osmux: %u", &osmux_cid) != 1) {
+	if (sscanf(line + 2 + 7, "%u", &osmux_cid) != 1) {
 		LOGP(DLMGCP, LOGL_ERROR, "Failed parsing Osmux in MGCP msg line: %s\n",
 		     line);
 		return -2;