[frogr] Restore `werror=true`, changed by mistake in the previous commit

[Mario Sanchez Prada <msanchez src gnome org>]

commit 27170f92a91039efadcf04f7ad88d8e909941069
Author: Mario Sanchez Prada <msanchez gnome org>
Date:   Thu Jan 9 11:08:59 2020 +0100

    Restore `werror=true`, changed by mistake in the previous commit

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 038c39e..c5e173d 100644
--- a/meson.build
+++ b/meson.build
@@ -3,7 +3,7 @@ project('frogr', 'c',
         license: 'GPL3',
         default_options: [
             'warnlevel=2',
-            'werror=false'
+            'werror=true'
         ])
 
 project_name = meson.project_name()