Fix: comparison of constant 1 with boolean expression is always false

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5353 43c1dc8c-776e-4df2-8ef1-6e829299be21
Endcall when receiving mediastatus!=0 while handling openreceive_channel, check if we have a valid channel before calling close_receive_channel

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5354 43c1dc8c-776e-4df2-8ef1-6e829299be21