[glib] meson: Add 'charsetalias-dir' option mirroring the autotools one

[Nirbheek Chauhan <nirbheekc src gnome org>]

commit c603ba301d2e236bdee04b5c78d3204a71609eed
Author: Nirbheek Chauhan <nirbheek centricular com>
Date:   Wed Nov 22 04:40:10 2017 +0530

    meson: Add 'charsetalias-dir' option mirroring the autotools one
    
    This fixes the build again.

 glib/libcharset/meson.build |    7 ++++++-
 meson_options.txt           |    2 ++
 2 files changed, 8 insertions(+), 1 deletions(-)
---
diff --git a/glib/libcharset/meson.build b/glib/libcharset/meson.build
index e926f21..9e16c35 100644
--- a/glib/libcharset/meson.build
+++ b/glib/libcharset/meson.build
@@ -1,4 +1,9 @@
+charsetalias_dir = get_option('charsetalias-dir')
+if charsetalias_dir == ''
+  charsetalias_dir = get_option('libdir')
+endif
+
 charset_lib = static_library('charset', 'localcharset.c',
   include_directories : configinc,
   pic : true,
-  c_args : [ '-DLIBDIR="@0@"'.format(get_option('libdir')) ] + glib_hidden_visibility_args)
+  c_args : [ '-DGLIB_CHARSETALIAS_DIR="@0@"'.format(charsetalias_dir) ] + glib_hidden_visibility_args)
diff --git a/meson_options.txt b/meson_options.txt
index 1811e8b..9284fff 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -8,3 +8,5 @@ option('enable-systemtap', type : 'boolean', value : false,
   description : 'include tracing support for systemtap')
 option('tapset-install-dir', type : 'string', value : '',
   description : 'path where systemtap tapsets are installed')
+option('charsetalias-dir', type : 'string', value : '',
+  description : 'directory for charset.alias file (libdir by default)')