[gthumb] meson: error when buildtype is not debug

[Paolo Bacchilega <paobac src gnome org>]

commit dae26923df676c8fa6a30622081d5359a6a0f3f5
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Fri Nov 29 13:20:39 2019 +0100

    meson: error when buildtype is not debug
    
    Closes #76

 meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/meson.build b/meson.build
index cfc9e420..2b5e68c2 100644
--- a/meson.build
+++ b/meson.build
@@ -333,6 +333,7 @@ if get_option('buildtype').contains('debug')
 else
   warn_deprecated = false
   test_c_args = [ '-Wall' ]
+  test_cpp_args = [ '-Wall' ]
 endif
 if not(warn_deprecated)
   test_c_args += [ '-Wno-deprecated-declarations' ]