perf clang: Support compile IR to BPF object and add testcase

getBPFObjectFromModule() is introduced to compile LLVM IR(Module)
to BPF object. Add new testcase for it.

Test result:
  $ ./buildperf/perf test -v clang
  51: builtin clang support                               :
  51.1: builtin clang compile C source to IR              :
  --- start ---
  test child forked, pid 21822
  test child finished with 0
  ---- end ----
  builtin clang support subtest 0: Ok
  51.2: builtin clang compile C source to ELF object      :
  --- start ---
  test child forked, pid 21823
  test child finished with 0
  ---- end ----
  builtin clang support subtest 1: Ok

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-15-wangnan0@huawei.com
[ Remove redundant "Test" from entry descriptions ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/clang.c

@@ -12,6 +12,10 @@ static struct {
 		.func = test__clang_to_IR,
 		.desc = "builtin clang compile C source to IR",
 	},
+	{
+		.func = test__clang_to_obj,
+		.desc = "builtin clang compile C source to ELF object",
+	},
 #endif
 };
 
@@ -33,7 +37,7 @@ int test__clang(int i __maybe_unused)
 	return TEST_SKIP;
 }
 #else
-int test__clang(int i __maybe_unused)
+int test__clang(int i)
 {
 	if (i < 0 || i >= (int)ARRAY_SIZE(clang_testcase_table))
 		return TEST_FAIL;