[gtk] tests: Fix comment for accuracy

[Emmanuele Bassi <ebassi src gnome org>]

commit 61fbd5b541140108f420c646bddcb447021eb54f
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Feb 6 10:41:49 2019 +0100

    tests: Fix comment for accuracy
    
    The command line for compiling testwindowsize has changed.

 tests/testwindowsize.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/tests/testwindowsize.c b/tests/testwindowsize.c
index 9f7b029435..22a8b4d792 100644
--- a/tests/testwindowsize.c
+++ b/tests/testwindowsize.c
@@ -1,4 +1,4 @@
-/*  gcc -g -Wall -O2 -o dialog-test dialog-test.c `pkg-config --cflags --libs gtk+-3.0` */
+/*  gcc -g -Wall -O2 -o dialog-test dialog-test.c `pkg-config --cflags --libs gtk4` */
 #include <gtk/gtk.h>
 
 static GtkWidget *window;