perf beauty: Add a generator for MS_ mount/umount's flag constants

perf beauty: Add a generator for MS_ mount/umount's flag constants

It'll use tools/include copy of linux/fs.h to generate a table to be
used by tools, initially by the 'mount' and 'umount' beautifiers in
'perf trace', but that could also be used to translate from a string
constant to the integer value to be used in a eBPF or tracefs tracepoint
filter.

When used without any args it produces:

  $ tools/perf/trace/beauty/mount_flags.sh
  static const char *mount_flags[] = {
	[1 ? (ilog2(1) + 1) : 0] = "RDONLY",
	[2 ? (ilog2(2) + 1) : 0] = "NOSUID",
	[4 ? (ilog2(4) + 1) : 0] = "NODEV",
	[8 ? (ilog2(8) + 1) : 0] = "NOEXEC",
	[16 ? (ilog2(16) + 1) : 0] = "SYNCHRONOUS",
	[32 ? (ilog2(32) + 1) : 0] = "REMOUNT",
	[64 ? (ilog2(64) + 1) : 0] = "MANDLOCK",
	[128 ? (ilog2(128) + 1) : 0] = "DIRSYNC",
	[1024 ? (ilog2(1024) + 1) : 0] = "NOATIME",
	[2048 ? (ilog2(2048) + 1) : 0] = "NODIRATIME",
	[4096 ? (ilog2(4096) + 1) : 0] = "BIND",
	[8192 ? (ilog2(8192) + 1) : 0] = "MOVE",
	[16384 ? (ilog2(16384) + 1) : 0] = "REC",
	[32768 ? (ilog2(32768) + 1) : 0] = "SILENT",
	[16 + 1] = "POSIXACL",
	[17 + 1] = "UNBINDABLE",
	[18 + 1] = "PRIVATE",
	[19 + 1] = "SLAVE",
	[20 + 1] = "SHARED",
	[21 + 1] = "RELATIME",
	[22 + 1] = "KERNMOUNT",
	[23 + 1] = "I_VERSION",
	[24 + 1] = "STRICTATIME",
	[25 + 1] = "LAZYTIME",
	[26 + 1] = "SUBMOUNT",
	[27 + 1] = "NOREMOTELOCK",
	[28 + 1] = "NOSEC",
	[29 + 1] = "BORN",
	[30 + 1] = "ACTIVE",
	[31 + 1] = "NOUSER",
  };
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-mgutbbkmip9gfnmd28ikg7xt@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>