perf trace: Beautify the 'level' argument of getsockopt

  # perf trace -e getsockopt
       0.000 ( 0.006 ms): systemd-resolv/1121 getsockopt(fd: 21, level: 1, optname: 17, optval: 0x7ffee2c0c6cc, optlen: 0x7ffee2c0c6c8) = 0
       0.301 ( 0.003 ms): systemd-resolv/1121 getsockopt(fd: 22, level: IP, optname: 14, optval: 0x7ffee2c0c1a0, optlen: 0x7ffee2c0c1a4) = -1 ENOTCONN (Transport endpoint is not connected)
       2.215 ( 0.005 ms): systemd-resolv/1121 getsockopt(fd: 21, level: 1, optname: 17, optval: 0x7ffee2c0c6cc, optlen: 0x7ffee2c0c6c8) = 0
       2.422 ( 0.005 ms): systemd-resolv/1121 getsockopt(fd: 22, level: IP, optname: 14, optval: 0x7ffee2c0c1a0, optlen: 0x7ffee2c0c1a4) = -1 ENOTCONN (Transport endpoint is not connected)
    1001.308 ( 0.006 ms): systemd-resolv/1121 getsockopt(fd: 21, level: 1, optname: 17, optval: 0x7ffee2c0c6cc, optlen: 0x7ffee2c0c6c8) = 0
    1001.586 ( 0.003 ms): systemd-resolv/1121 getsockopt(fd: 22, level: IP, optname: 14, optval: 0x7ffee2c0c1a0, optlen: 0x7ffee2c0c1a4) = -1 ENOTCONN (Transport endpoint is not connected)
    1001.647 ( 0.002 ms): systemd-resolv/1121 getsockopt(fd: 23, level: IP, optname: 14, optval: 0x7ffee2c0c1a0, optlen: 0x7ffee2c0c1a4) = -1 ENOTCONN (Transport endpoint is not connected)
    1003.868 ( 0.010 ms): systemd-resolv/1121 getsockopt(fd: 21, level: 1, optname: 17, optval: 0x7ffee2c0c6cc, optlen: 0x7ffee2c0c6c8) = 0
    1004.036 ( 0.006 ms): systemd-resolv/1121 getsockopt(fd: 22, level: IP, optname: 14, optval: 0x7ffee2c0c1a0, optlen: 0x7ffee2c0c1a4) = -1 ENOTCONN (Transport endpoint is not connected)
    1004.087 ( 0.002 ms): systemd-resolv/1121 getsockopt(fd: 23, level: IP, optname: 14, optval: 0x7ffee2c0c1a0, optlen: 0x7ffee2c0c1a4) = -1 ENOTCONN (Transport endpoint is not connected)
  ^C#

So the simple straight STRARRAY method is not enough as SOL_SOCKET is
'1' in most architectures but some use 0xffff (alpha, mips, parisc and
sparc), so a followup patch will create a specialized scnprintf to cover
that.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>