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>

tools/perf/builtin-trace.c

@@ -979,6 +979,8 @@ static struct syscall_fmt syscall_fmts[] = {
 	  .arg = { [2] = { .scnprintf = SCA_GETRANDOM_FLAGS, /* flags */ }, }, },
 	{ .name	    = "getrlimit",
 	  .arg = { [0] = STRARRAY(resource, rlimit_resources), }, },
+	{ .name	    = "getsockopt",
+	  .arg = { [1] = STRARRAY(level, socket_level), }, },
 	{ .name	    = "gettid",	    .errpid = true, },
 	{ .name	    = "ioctl",
 	  .arg = {