meson: add "filter_names" in features when needed

When filter_names option is enabled we now see that in the output of
 "pcscd --version".

Thanks to leuthold-at-ehex-de for the bug report
" pcscd build feature "filter" not reported #202 "
#202

meson.build

@@ -19,7 +19,6 @@ conf_data = configuration_data({
  'PCSCLITE_HP_DROPDIR' : '"' + get_option('usbdropdir') + '"',
  'HAVE_NANOSLEEP' : true,
  'NO_LOG' : get_option('embedded'),
- 'FILTER_NAMES' : get_option('filter_names'),
  })
 # for generated files from .in templates
 sbindir = join_paths(get_option('prefix') , get_option('sbindir'))
@@ -56,6 +55,11 @@ if get_option('serial')
  features += 'serial'
 endif
 
+if get_option('filter_names')
+ conf_data.set('FILTER_NAMES', true)
+ features += 'filter_names'
+endif
+
 # flex generator
 gen_flex = generator(find_program('flex'),
  output : '@BASENAME@.c',