perf record: Fix -c/-F options for cpu event aliases

The Intel PMU event aliases have a implicit period= specifier to set the
default period.

Unfortunately this breaks overriding these periods with -c or -F,
because the alias terms look like they are user specified to the
internal parser, and user specified event qualifiers override the
command line options.

Track that they are coming from aliases by adding a "weak" state to the
term. Any weak terms don't override command line options.

I only did it for -c/-F for now, I think that's the only case that's
broken currently.

Before:

$ perf record -c 1000 -vv -e uops_issued.any
...
  { sample_period, sample_freq }   2000003

After:

$ perf record -c 1000 -vv -e uops_issued.any
...
  { sample_period, sample_freq }   1000

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20171020202755.21410-2-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.h

@@ -101,6 +101,9 @@ struct parse_events_term {
 	/* error string indexes for within parsed string */
 	int err_term;
 	int err_val;
+
+	/* Coming from implicit alias */
+	bool weak;
 };
 
 struct parse_events_error {