perf test: Add an 'import perf' test shell script

perf test: Add an 'import perf' test shell script

The 'import perf' test needs to set up a path to the python module as
well as to know the python command to invoke.

These are hard coded at build time to be build a directory and the
python used in the build, which is less than desirable.

Avoid the hard coded values by reusing the existing shell script python
setup and determine a potential built python module via the path of the
perf executable.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Collin Funk <collin.funk1@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>