GSS-NTLMSSP vulnerable to incorrect free when decoding target information

GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, an incorrect free when decoding target information can trigger a denial of service. The error condition incorrectly assumes the `cb` and `sh` buffers contain a copy of the data that needs to be freed. However, that is not the case. This vulnerability can be triggered via the main `gss_accept_sec_context` entry point. This will likely trigger an assertion failure in `free`, causing a denial-of-service. This issue is fixed in version 1.2.0.