[at-spi2-atk] Set C standard to gnu99

[Mike Gorse <mgorse src gnome org>]

commit 0b4b3d010ea33c77627aff9569049d676d1c9add
Author: Mike Gorse <mgorse suse com>
Date:   Sat Feb 29 16:08:59 2020 -0600

    Set C standard to gnu99
    
    Fixes https://gitlab.gnome.org/GNOME/at-spi2-atk/issues/10

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 358381a..0a0b961 100644
--- a/meson.build
+++ b/meson.build
@@ -4,7 +4,7 @@ project('at-spi2-atk', 'c',
         default_options: [
           'buildtype=debugoptimized',
           'warning_level=1',
-          'c_std=c99',
+          'c_std=gnu99',
         ],
         meson_version : '>= 0.40.1')