Fix potential NULL pointer dereference

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5093 43c1dc8c-776e-4df2-8ef1-6e829299be21
Fix potential memory leak for context variable

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5094 43c1dc8c-776e-4df2-8ef1-6e829299be21
Suppress compilation warning about printf/unsigned int

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5095 43c1dc8c-776e-4df2-8ef1-6e829299be21