perf bpf: Enclose libbpf.h include within HAVE_LIBBPF_SUPPORT

As it uses the 'deprecated' attribute in a way that breaks the build
with old gcc compilers, so to continue being able to build in such
systems where NO_LIBBPF=1 is being used, enclose it under
HAVE_LIBBPF_SUPPORT.

1 centos:6 : FAIL gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-23)
2 oraclelinux:6 : FAIL gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-23.0.1)

CC /tmp/build/perf/builtin-record.o
In file included from util/bpf-loader.h:11,
from builtin-record.c:39:
/git/linux/tools/lib/bpf/libbpf.h:203: error: wrong number of arguments specified for 'deprecated' attribute

Cc: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/bpf-loader.h

···
 
 #include <linux/compiler.h>
 #include <linux/err.h>
+
+#ifdef HAVE_LIBBPF_SUPPORT
 #include <bpf/libbpf.h>
 
 enum bpf_loader_errno {
···
 	BPF_LOADER_ERRNO__OBJCONF_MAP_IDX2BIG,	/* Index too large */
 	__BPF_LOADER_ERRNO__END,
 };
+#endif // HAVE_LIBBPF_SUPPORT
 
 struct evsel;
 struct evlist;

tools/perf/util/parse-events.c

···
 	return ret;
 }
 
+#ifdef HAVE_LIBBPF_SUPPORT
 struct __add_bpf_event_param {
 	struct parse_events_state *parse_state;
 	struct list_head *list;
···
 		list_splice_tail(&obj_head_config, head_config);
 	return err;
 }
+#else // HAVE_LIBBPF_SUPPORT
+int parse_events_load_bpf_obj(struct parse_events_state *parse_state,
+			      struct list_head *list __maybe_unused,
+			      struct bpf_object *obj __maybe_unused,
+			      struct list_head *head_config __maybe_unused)
+{
+	parse_events__handle_error(parse_state->error, 0,
+				   strdup("BPF support is not compiled"),
+				   strdup("Make sure libbpf-devel is available at build time."));
+	return -ENOTSUP;
+}
+
+int parse_events_load_bpf(struct parse_events_state *parse_state,
+			  struct list_head *list __maybe_unused,
+			  char *bpf_file_name __maybe_unused,
+			  bool source __maybe_unused,
+			  struct list_head *head_config __maybe_unused)
+{
+	parse_events__handle_error(parse_state->error, 0,
+				   strdup("BPF support is not compiled"),
+				   strdup("Make sure libbpf-devel is available at build time."));
+	return -ENOTSUP;
+}
+#endif // HAVE_LIBBPF_SUPPORT
 
 static int
 parse_breakpoint_type(const char *type, struct perf_event_attr *attr)