meson: enable nls support

This was not implemented in meson, probably because it's a mess to do
before version 0.59.0. Speaking of which, restrict it to that.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

meson.build

@@ -272,6 +272,18 @@ lib_readline_static = dependency(
   static : true,
   required : need_static_libs ? get_option('readline') : disabler())
 
+if meson.version().version_compare('>= 0.59.0')
+  lib_intl = dependency(
+    'intl',
+    required : get_option('nls'))
+  conf.set('ENABLE_NLS', lib_intl.found() ? 1 : false)
+else
+  if get_option('nls').enabled()
+    error('nls is not supported with meson before 0.59.0')
+  endif
+  lib_intl = dependency('', required : false)
+endif
+
 lib_user = dependency(
   'libuser',
   version : '>= 0.58',

meson_options.txt

@@ -9,6 +9,7 @@ option('cryptsetup',  type : 'feature')
 option('cryptsetup-dlopen',  type : 'feature')
 option('zlib',        type : 'feature')
 option('readline',    type : 'feature')
+option('nls',         type : 'feature')
 option('libutil',     type : 'feature')
 option('libutempter', type : 'feature')
 option('libpcre2-posix',     type : 'feature')