tools: Adopt noinline from kernel sources

To have a more compact way to ask the compiler not to inline a function
and to make tools/ source code look like kernel code.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-bis4pqxegt6gbm5dlqs937tn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/bp_signal_overflow.c

@@ -28,8 +28,7 @@
 
 static int overflows;
 
-__attribute__ ((noinline))
-static int test_function(void)
+static noinline int test_function(void)
 {
 	return time(NULL);
 }