[vte] build: Fix netbsd define

[Christian Persch <chpe src gnome org>]

commit e0675c6533c23c0bdda6531617428cdfe5979ad9
Author: Christian Persch <chpe src gnome org>
Date:   Fri Sep 23 16:24:57 2022 +0200

    build: Fix netbsd define

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 49b849e0..02c8ba40 100644
--- a/meson.build
+++ b/meson.build
@@ -232,7 +232,7 @@ if system == 'freebsd'
 
 elif system == 'netbsd'
   libc_feature_defines += [
-    '_NETBSD_SOURCE',
+    ['_NETBSD_SOURCE', '1'],
   ]
 endif