perf llvm: Extract helpers in llvm-utils.c

The following commits will use builtin clang to compile BPF scripts.

llvm__get_kbuild_opts() and llvm__get_nr_cpus() are extracted to help
building '-DKERNEL_VERSION_CODE' and '-D__NR_CPUS__' macros.

Doing object dumping in bpf loader, so further builtin clang compiling
needn't consider it.

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/20161126070354.141764-7-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index a5fd275..cf16b941 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -90,6 +90,10 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source)
 		if (err)
 			return ERR_PTR(-BPF_LOADER_ERRNO__COMPILE);
 		obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, filename);
+
+		if (!IS_ERR(obj) && llvm_param.dump_obj)
+			llvm__dump_obj(filename, obj_buf, obj_buf_sz);
+
 		free(obj_buf);
 	} else
 		obj = bpf_object__open(filename);