With this patch valgrind compains about leaked 43 bytes but
without the patch glibc reports double free the second time
newcamd_login() is called and crashes the program. Since the
leak is not bad (it is a static buffer allocated by glibc) just
ignore valgrind in this case.

If the message is NULL just continue. Breaking out of the loop is
wrong because it stops the ecm/processing thread and leaves tsdecrypt
in a non working state.

no-output-filter better describes what the parameter does.
Also fix man page description. output-filter still works but
it is undocumented and kept only for backwards compatability.

Handle errors in generic camd code instead of protocol code.

This makes do_emm() and do_ecm() take the same parameters. The next
step is to make them take struct camd_msg as single parameter.

This move is in preparation to use struct camd_msg in camd ops.