perf bench uprobe: Fix potential use of memory after free

Found by clang-tidy:
```
bench/uprobe.c:98:3: warning: Use of memory after it is freed [clang-analyzer-unix.Malloc]
bench_uprobe_bpf__destroy(skel);
```

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: llvm@lists.linux.dev
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Tom Rix <trix@redhat.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20231009183920.200859-6-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

perf bench uprobe trace_printk: Add entry attaching an BPF program that does a trace_printk

[root@five ~]# perf bench uprobe all
# Running uprobe/baseline benchmark...
# Executed 1,000 usleep(1000) calls
Total time: 1,053,963 usecs

1,053.963 usecs/op

# Running uprobe/empty benchmark...
# Executed 1,000 usleep(1000) calls
Total time: 1,056,293 usecs +2,330 to baseline

1,056.293 usecs/op 2.330 usecs/op to baseline

# Running uprobe/trace_printk benchmark...
# Executed 1,000 usleep(1000) calls
Total time: 1,056,977 usecs +3,014 to baseline +684 to previous

1,056.977 usecs/op 3.014 usecs/op to baseline 0.684 usecs/op to previous

[root@five ~]#

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andre Fredette <anfredet@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Dave Tucker <datucker@redhat.com>
Cc: Derek Barbosa <debarbos@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20230719204910.539044-6-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf bench uprobe empty: Add entry attaching an empty BPF program

Using libbpf and a BPF skel:

# perf bench uprobe all
# Running uprobe/baseline benchmark...
# Executed 1,000 usleep(1000) calls
Total time: 1,055,618 usecs

1,055.618 usecs/op
# Running uprobe/empty benchmark...
# Executed 1,000 usleep(1000) calls
Total time: 1,057,146 usecs +1,528 to baseline

1,057.146 usecs/op
#

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andre Fredette <anfredet@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Dave Tucker <datucker@redhat.com>
Cc: Derek Barbosa <debarbos@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20230719204910.539044-5-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf bench uprobe: Show diff to previous

Will be useful to show the incremental overhead as we do more stuff in
the BPF program attached to the uprobes.

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andre Fredette <anfredet@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Dave Tucker <datucker@redhat.com>
Cc: Derek Barbosa <debarbos@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20230719204910.539044-4-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf bench uprobe: Print diff to baseline

This is just prep work to show the diff to the unmodified workload.

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andre Fredette <anfredet@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Dave Tucker <datucker@redhat.com>
Cc: Derek Barbosa <debarbos@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20230719204910.539044-3-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf bench uprobe: Add benchmark to test uprobe overhead

This just adds the initial "workload", a call to libc's usleep(1000us)
function:

$ perf stat --null perf bench uprobe all
# Running uprobe/baseline benchmark...
# Executed 1000 usleep(1000) calls
Total time: 1053533 usecs

1053.533 usecs/op

Performance counter stats for 'perf bench uprobe all':

1.061042896 seconds time elapsed

0.001079000 seconds user
0.006499000 seconds sys

$

More entries will be added using a BPF skel to add various uprobes to
the usleep() function.

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andre Fredette <anfredet@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Dave Tucker <datucker@redhat.com>
Cc: Derek Barbosa <debarbos@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20230719204910.539044-2-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>