perf test: Disable breakpoint signal tests for powerpc

The following tests are failing on powerpc:

  # perf test break
  18: Breakpoint overflow signal handler  : FAILED!
  19: Breakpoint overflow sampling        : FAILED!

The powerpc kenel so far does not have support to even create
instruction breakpoints using the perf event interface, so those tests
fail early in the config phase.

I added a '->is_supported()' callback to test struct to be able to
disable specific tests. It seems better than putting ifdefs directly to
the test array.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20170601205450.GA398@krava
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index 6318596..5773638 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -34,6 +34,7 @@ struct test {
 		int (*get_nr)(void);
 		const char *(*get_desc)(int subtest);
 	} subtest;
+	bool (*is_supported)(void);
 };
 
 /* Tests */
@@ -99,6 +100,8 @@ const char *test__clang_subtest_get_desc(int subtest);
 int test__clang_subtest_get_nr(void);
 int test__unit_number__scnprint(int subtest);
 
+bool test__bp_signal_is_supported(void);
+
 #if defined(__arm__) || defined(__aarch64__)
 #ifdef HAVE_DWARF_UNWIND_SUPPORT
 struct thread;