Revert "drop (now) unused code"

This reverts commit 2b30cbdfa83c20045ef92f53e88441dda185591b.

Reason for revert: Older versions of osmo-msc were actually calling map_codec_to_pt().

Change-Id: Ifff31012b327d40ed0b1559d5cf4f320784a4061
Related: https://jenkins.osmocom.org/jenkins/job/Osmocom-build-tags-against-master/1792/console
diff --git a/tests/mgcp_client/mgcp_client_test.err b/tests/mgcp_client/mgcp_client_test.err
index 9e98792..94fe351 100644
--- a/tests/mgcp_client/mgcp_client_test.err
+++ b/tests/mgcp_client/mgcp_client_test.err
@@ -128,6 +128,10 @@
 body: "some mgcp header data\r\nand header params\r\n\r\nc=IN IP4 \r\n"
 DLMGCP Failed to parse MGCP response header (audio ip)
 got rc=-22
+DLMGCP ptmap contains illegal mapping: codec=113 maps to pt=2
+DLMGCP ptmap contains illegal mapping: codec=0 maps to pt=100
+DLMGCP ptmap contains illegal mapping: codec=113 maps to pt=2
+DLMGCP ptmap contains illegal mapping: codec=0 maps to pt=100
 DLMGCP MGW(mgw) MGCP client: using endpoint domain '@mgw'
 DLMGCP MGW(mgw) Cannot compose MGCP e1-endpoint name (ds/e1-15/s-1/su128-0@mgw), rate(128)/offset(0) combination is invalid!
 DLMGCP MGW(mgw) Cannot compose MGCP e1-endpoint name (ds/e1-15/s-1/su8-16@mgw), rate(8)/offset(16) combination is invalid!