perf test: Auto bump rlimit(MEMLOCK) for BPF test sake

perf test: Auto bump rlimit(MEMLOCK) for BPF test sake

I noticed that the 'perf test bpf' was failing:

  # perf test bpf
  41: BPF filter                                            :
  41.1: Basic BPF filtering                                 : Skip
  41.2: BPF pinning                                         : Skip
  41.3: BPF prologue generation                             : Skip
  41.4: BPF relocation checker                              : Skip
  # ulimit -l
  64
  #

Using verbose mode we get just a line bout -EPERF being returned from
libbpf's bpf_load_program_xattr(), that ends up being used in 'perf
test bpf' initial program loading capability query:

  Missing basic BPF support, skip this test: Operation not permitted

Not that informative, but on a separate problem when creating BPF maps
bumping rlimit(MEMLOCK) helped, so I tried it here as well, works:

  # ulimit -l 128
  # perf test bpf
  41: BPF filter                                            :
  41.1: Basic BPF filtering                                 : Ok
  41.2: BPF pinning                                         : Ok
  41.3: BPF prologue generation                             : Ok
  41.4: BPF relocation checker                              : Ok
  #

So use the recently added rlimit__bump_memlock() helper:

  # ulimit -l 64
  # perf test bpf
  41: BPF filter                                            :
  41.1: Basic BPF filtering                                 : Ok
  41.2: BPF pinning                                         : Ok
  41.3: BPF prologue generation                             : Ok
  41.4: BPF relocation checker                              : Ok
  # ulimit -l
  64
  #

I.e. the bumping of memlock is restricted to the 'perf test' instance,
not changing the global value.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-b9fubkhr4jm192lu7y8hgjvo@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>