perf report: Fix sample type validation for synthesized callchains

Processing instruction tracing data (e.g. Intel PT) can synthesize
callchains e.g.

	$ perf record -e intel_pt//u uname
	$ perf report --stdio --itrace=ige

However perf report's callgraph option gets extra validation, so:

	$ perf report --stdio --itrace=ige -gflat
	Error:
	Selected -g or --branch-history but no callchain data. Did
	you call 'perf record' without -g?
	# To display the perf.data header info,
	# please use --header/--header-only options.
	#

Fix the validation to know about instruction tracing options so
above command works.

A side-effect of the change is that the default option to
accumulate the callchain of child functions comes into force.
To get the previous behaviour the --no-children option can be
used e.g.

       $ perf report --stdio --itrace=ige -gflat --no-children

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1443186956-18718-3-git-send-email-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>