[vte] build: Add define for darwin

[Christian Persch <chpe src gnome org>]

commit 8ef3f6b2f8043d28cbc82520eb094f09333b26ae
Author: Christian Persch <chpe src gnome org>
Date:   Fri Sep 23 16:24:57 2022 +0200

    build: Add define for darwin
    
    Fixes: https://gitlab.gnome.org/GNOME/vte/-/issues/2592

 meson.build | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/meson.build b/meson.build
index 02c8ba40..f36f93d5 100644
--- a/meson.build
+++ b/meson.build
@@ -230,6 +230,12 @@ if system == 'freebsd'
 
   libc_feature_defines = []
 
+elif system == 'darwin'
+  # See issue #2592
+  libc_feature_defines += [
+    ['_DARWIN_C_SOURCE', '1'],
+  ]
+
 elif system == 'netbsd'
   libc_feature_defines += [
     ['_NETBSD_SOURCE', '1'],