[libsoup] meson: Explicitly set encoding to utf-8 for non-English locale

[Tomas Popela <tpopela src gnome org>]

commit 6b5945ea1b60876a9cd6fd5fcff9cffb7aa62fb9
Author: Seungha Yang <seungha yang navercorp com>
Date:   Tue Apr 9 22:19:11 2019 +0900

    meson: Explicitly set encoding to utf-8 for non-English locale
    
    Visual Studio 2019 handle it as an error.
    
    FAILED: subprojects/libsoup/libsoup/1b29d39@@soup-2.4@sha/meson-generated_.._soup-enum-types.c.obj
    cl @subprojects/libsoup/libsoup/1b29d39@@soup-2.4@sha/meson-generated_.._soup-enum-types.c.obj.rsp
    subprojects\glib\glib/gmacros.h(824): error C4819:
        The file contains a character that cannot be represented in the current code page (949).
        Save the file in Unicode format to prevent data loss

 meson.build | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/meson.build b/meson.build
index 6ca8b699..120c9c01 100644
--- a/meson.build
+++ b/meson.build
@@ -39,6 +39,9 @@ cc = meson.get_compiler('c')
 # Enable extra warnings if compiler supports them.
 if cc.get_id() == 'msvc'
   common_flags += ['/FImsvc_recommended_pragmas.h']
+
+  # set the input encoding to utf-8
+  add_project_arguments(cc.get_supported_arguments(['/utf-8']), language: 'c')
 else
   test_cflags = [
       '-Wall',