perf report: Support output in nanoseconds

Upcoming changes add timestamp output in perf report. Add a --ns
argument similar to perf script to support nanoseconds resolution when
needed.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20190305144758.12397-5-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.c

@@ -39,6 +39,7 @@ int vmlinux_path__nr_entries;
 char **vmlinux_path;
 
 struct symbol_conf symbol_conf = {
+	.nanosecs		= false,
 	.use_modules		= true,
 	.try_vmlinux_path	= true,
 	.demangle		= true,