perf test: Add option to change objdump binary

All of the other Perf subcommands that use objdump have an option to
specify the binary, so add the same option to 'perf test'.

This is useful if you have built the kernel with a different toolchain
to the system one, where the system objdump may fail to disassemble
vmlinux.

Now this can be fixed with something like this:

  $ perf test --objdump llvm-objdump "object code reading"

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20231106151051.129440-2-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/tests.h

@@ -207,5 +207,6 @@ DECLARE_WORKLOAD(brstack);
 DECLARE_WORKLOAD(datasym);
 
 extern const char *dso_to_test;
+extern const char *test_objdump_path;
 
 #endif /* TESTS_H */