[libwnck] meson, docs: pass deprecated-guards without quotes

[Marco Trevisan <marcotrevi src gnome org>]

commit 2fd99e8bee2415fc8b11097b9871eced217ee17c
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed Nov 7 06:24:14 2018 -0500

    meson, docs: pass deprecated-guards without quotes
    
    As per recent meson changes, this would not work properly

 doc/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/doc/meson.build b/doc/meson.build
index e28db18..958137c 100644
--- a/doc/meson.build
+++ b/doc/meson.build
@@ -11,7 +11,7 @@ gnome.gtkdoc(meson.project_name(),
   ignore_headers: ['wnck-enum-types.h', 'version.h'],
   scan_args: [
     '--rebuild-types',
-    '--deprecated-guards="WNCK_DISABLE_DEPRECATED"'
+    '--deprecated-guards=WNCK_DISABLE_DEPRECATED'
   ],
   install: true,
   module_version: MODULE_VERSION,