Add a test for decoding self-modifying code using a jitdump file.

The test creates a workload that uses self-modifying code and generates its
own jitdump file.  The result is processed with perf inject --jit and
checked for decoding errors.

Note the test will fail without patch "perf inject: Fix GEN_ELF_TEXT_OFFSET
for jit" applied.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20221014170905.64069-6-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>