perf beauty mmap: Print mmap's 'offset' arg in hexadecimal

Also to make it match 'strace' output, for regression testing.

Both now produce this option, when 'perf trace' uses a .perfconfig
asking for the strace like output:

  mmap(0x7faf66e6a000, 1363968, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7faf66e6a000

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-27qhouo1kaac2iyl85nfnsf5@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -756,7 +756,8 @@ static struct syscall_fmt {
 	.alias = "old_mmap",
 #endif
 	  .arg = { [2] = { .scnprintf = SCA_MMAP_PROT,	/* prot */ },
-		   [3] = { .scnprintf = SCA_MMAP_FLAGS,	/* flags */ }, }, },
+		   [3] = { .scnprintf = SCA_MMAP_FLAGS,	/* flags */ },
+		   [5] = { .scnprintf = SCA_HEX,	/* offset */ }, }, },
 	{ .name	    = "mount",
 	  .arg = { [0] = { .scnprintf = SCA_FILENAME, /* dev_name */ },
 		   [3] = { .scnprintf = SCA_MOUNT_FLAGS, /* flags */