perf bpf_skel: Do not use typedef to avoid error on old clang

When building bpf_skel with clang-10, typedef causes confusions like:

  libbpf: map 'prev_readings': unexpected def kind var.

Fix this by removing the typedef.

Fixes: 7fac83a ("perf stat: Introduce 'bperf' to share hardware PMCs with BPF")
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/lkml/BEF5C312-4331-4A60-AEC0-AD7617CB2BC4@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: liu-song-6

tools/perf/util/bpf_skel/bperf.h

@@ -3,11 +3,21 @@
 #include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
-#include "bperf.h"
 #include "bperf_u.h"
 
-reading_map diff_readings SEC(".maps");
-reading_map accum_readings SEC(".maps");
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(struct bpf_perf_event_value));
+	__uint(max_entries, 1);
+} diff_readings SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(struct bpf_perf_event_value));
+	__uint(max_entries, 1);
+} accum_readings SEC(".maps");
 
 struct {
 	__uint(type, BPF_MAP_TYPE_HASH);

tools/perf/util/bpf_skel/bperf_follower.bpf.c

@@ -3,7 +3,6 @@
 #include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
-#include "bperf.h"
 
 struct {
 	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
@@ -12,8 +11,19 @@ struct {
 	__uint(map_flags, BPF_F_PRESERVE_ELEMS);
 } events SEC(".maps");
 
-reading_map prev_readings SEC(".maps");
-reading_map diff_readings SEC(".maps");
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(struct bpf_perf_event_value));
+	__uint(max_entries, 1);
+} prev_readings SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(struct bpf_perf_event_value));
+	__uint(max_entries, 1);
+} diff_readings SEC(".maps");
 
 SEC("raw_tp/sched_switch")
 int BPF_PROG(on_switch)