Un-confuse clang checker.
seccomp-allow recvfrom, needed for non-TLS sockets.
Use TLSv1_2. Newer is better.
rpc_C_Finalize: Fix return value.

This function returned an uninitialized return value in case no
sessions had been opened by the application.
Avoid redefining DEBUG_OUTPUT.
Remove redundant code.
Merge branch 'master' of github.com:SUNET/pkcs11-proxy