[gimp-macos-build] Force utf-8 charset to build meson correctly

[Alex Samorukov <asamorukov src gnome org>]

commit 9c2185f01d076141042aaabd9f93aa6c361d94ad
Author: Oleksii Samorukov <oleksii_samorukov mckinsey com>
Date:   Thu Oct 31 09:37:15 2019 +0100

    Force utf-8 charset to build meson correctly

 jhbuildrc-gtk-osx-gimp | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/jhbuildrc-gtk-osx-gimp b/jhbuildrc-gtk-osx-gimp
index 069d7c5..12744ef 100644
--- a/jhbuildrc-gtk-osx-gimp
+++ b/jhbuildrc-gtk-osx-gimp
@@ -159,6 +159,8 @@ moduleset = 'https://gitlab.gnome.org/samm-git/gtk-osx/raw/fork-test/modulesets-
 
 # force python 3.6 for the libxml2 to avoid build issues
 module_extra_env['libxml2'] = { "ac_cv_path_PYTHON": "python3.6" }
+# meson needs UTF-8 charset for build python scripts to work correctly
+module_extra_env['meson'] = { "LC_ALL": "en_US.UTF-8" }
 
 class _cmd_bootstrap_gtk_osx_gimp(jhbuild.commands.base.cmd_build):
     doc = 'Build buildsystem tools not provided by MacOS.'