patch 9.0.1453: typos in source code and tests

Problem:    Typos in source code and tests.
Solution:   Fi the typos. (Dominique Pellé, closes #12217)
diff --git a/src/gui_haiku.cc b/src/gui_haiku.cc
index 78a444a..6b035a5 100644
--- a/src/gui_haiku.cc
+++ b/src/gui_haiku.cc
@@ -4518,7 +4518,7 @@
 	    //	when we add a BMenu to another Menu, it creates the interconnecting BMenuItem
 	    tmp->AddItem(bmenu);
 
-	    //	Now its safe to query the menu for the associated MenuItem....
+	    //	Now it's safe to query the menu for the associated MenuItem...
 	    menu->id = tmp->FindItem((const char *) menu->dname);
 
 	}