selftests/ftrace: Distinguish between hist and synthetic event checks

selftests/ftrace: Distinguish between hist and synthetic event checks

With synthetic events now a separate config item as a result of
'tracing: Move synthetic events to a separate file', tests that use
both need to explicitly check for hist trigger support rather than
relying on hist triggers to pull in synthetic events.

Add an additional hist trigger check to all the trigger tests that now
require it, otherwise they'll fail if synthetic events but not hist
triggers are enabled.

Link: http://lkml.kernel.org/r/af36c539006ef2768114b4ed38e6b054f7c7a3bd.1590693308.git.zanussi@kernel.org
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>