bpf: Fix sample_flags for bpf_perf_event_output

* Raw data is also filled by bpf_perf_event_output.
* Add sample_flags to indicate raw data.
* This eliminates the segfaults as shown below:
  Run ./samples/bpf/trace_output
  BUG pid 9 cookie 1001000000004 sized 4
  BUG pid 9 cookie 1001000000004 sized 4
  BUG pid 9 cookie 1001000000004 sized 4
  Segmentation fault (core dumped)

Fixes: 838d9bb ("perf: Use sample_flags for raw_data")
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/r/20221007081327.1047552-1-sumanthk@linux.ibm.com

Author: sumanthkorikkar

kernel/trace/bpf_trace.c

@@ -687,6 +687,7 @@ BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
 
 	perf_sample_data_init(sd, 0, 0);
 	sd->raw = &raw;
+	sd->sample_flags |= PERF_SAMPLE_RAW;
 
 	err = __bpf_perf_event_output(regs, map, flags, sd);
 
@@ -745,6 +746,7 @@ u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
 	perf_fetch_caller_regs(regs);
 	perf_sample_data_init(sd, 0, 0);
 	sd->raw = &raw;
+	sd->sample_flags |= PERF_SAMPLE_RAW;
 
 	ret = __bpf_perf_event_output(regs, map, flags, sd);
 out: