After gnulib update sed stopped matching `[[:space:]]*+' as before,
causing the following compilation error:

  In file included from builtin-trace.c:719:
  trace/beauty/generated/fsconfig_arrays.c:2:3: error: expected expression before ']' token
      2 |  [] = "",
	|   ^
  trace/beauty/generated/fsconfig_arrays.c:2:3: error: array index in initializer not of integer type
  trace/beauty/generated/fsconfig_arrays.c:2:3: note: (near initialization for 'fsconfig_cmds')

Fix this by correcting the regular expression used in the generator.
Also, clean up the script by removing redundant egrep, xargs, and printf
invocations.

Committer testing:

Continues to work:

  $ cat tools/perf/trace/beauty/fsconfig.sh
  #!/bin/sh
  # SPDX-License-Identifier: LGPL-2.1

  if [ $# -ne 1 ] ; then
  	linux_header_dir=tools/include/uapi/linux
  else
  	linux_header_dir=$1
  fi

  linux_mount=${linux_header_dir}/mount.h

  printf "static const char *fsconfig_cmds[] = {\n"
  ms='[[:space:]]*'
  sed -nr "s/^${ms}FSCONFIG_([[:alnum:]_]+)${ms}=${ms}([[:digit:]]+)${ms},.*/\t[\2] = \"\1\",/p" \
  	${linux_mount}
  printf "};\n"
  $ tools/perf/trace/beauty/fsconfig.sh
  static const char *fsconfig_cmds[] = {
  	[0] = "SET_FLAG",
  	[1] = "SET_STRING",
  	[2] = "SET_BINARY",
  	[3] = "SET_PATH",
  	[4] = "SET_PATH_EMPTY",
  	[5] = "SET_FD",
  	[6] = "CMD_CREATE",
  	[7] = "CMD_RECONFIGURE",
  };
  $

Fixes: d3529300 ("perf beauty: Add generator for fsconfig's 'cmd' arg values")
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
Co-authored-by: Dmitry V. Levin <ldv@altlinux.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lore.kernel.org/lkml/20210414182723.1670663-1-vt@altlinux.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>