ftrace/selftest: make unresolved cases cause failure if --fail-unresolved set

Currently, ftracetest will return 1 (failure) if any unresolved cases
are encountered.  The unresolved status results from modules and
programs not being available, and as such does not indicate any
issues with ftrace itself.  As such, change the behaviour of
ftracetest in line with unsupported cases; if unsupported cases
happen, ftracetest still returns 0 unless --fail-unsupported.  Here
--fail-unresolved is added and the default is to return 0 if
unresolved results occur.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>