To include IO-only and backtrace modes to test different code paths.

  $ sudo perf test -vv timechart
  135: perf timechart tests                        : Running
  135: perf timechart tests:
  ---- start ----
  test child forked, pid 2413665
  perf timechart Basic test
  perf timechart Basic test [Success]
  perf timechart IO-only test
  perf timechart IO-only test [Success]
  perf timechart Backtrace test
  perf timechart Backtrace test [Success]
  ---- end(0) ----
  135: perf timechart tests                        : Ok

  === Test Summary ===
  Passed main tests : 1
  Passed subtests   : 0
  Skipped tests     : 0
  Failed tests      : 0

Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Basic coverage for `perf timechart` doing a record and then a basic
sanity test of the generated SVG file.

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>