[polari] build: Shut up g-ir-scanner output

[Florian Müllner <fmuellner src gnome org>]

commit 4d318459d29a463cfc404372ef1e12fc71127938
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon May 29 22:18:05 2017 +0200

    build: Shut up g-ir-scanner output
    
    The regular command output just buries any warnings, so pass an
    extra switch to turn it off.

 src/meson.build |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/meson.build b/src/meson.build
index 6135230..eae686e 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -61,6 +61,7 @@ gnome.generate_gir(libpolari,
   symbol_prefix: 'polari',
   identifier_prefix: 'Polari',
   includes: ['Gio-2.0', 'Gtk-3.0', 'TelepathyGLib-0.12'],
+  extra_args: '--quiet',
   install_dir_gir: girdir,
   install_dir_typelib: typelibdir,
   install: true