[Ada] Do not warn about unused global declarations

[Eric Botcazou]

After the merge of the debug-early branch, the Ada compiler now issues 
warnings about unused global declarations (check_global_declaration is now 
invoked in Ada too).  That's undesirable, since the front-end proper already 
does it and its messages are superior.

Tested on x86_64-suse-linux, applied on the mainline.


2015-06-19  Eric Botcazou  <ebotca...@adacore.com>

        * gcc-interface/misc.c (LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): Define.


-- 
Eric Botcazou
Index: gcc-interface/misc.c
===================================================================
--- gcc-interface/misc.c	(revision 224602)
+++ gcc-interface/misc.c	(working copy)
@@ -1002,6 +1002,8 @@ gnat_init_ts (void)
 #define LANG_HOOKS_DEEP_UNSHARING	true
 #undef  LANG_HOOKS_INIT_TS
 #define LANG_HOOKS_INIT_TS		gnat_init_ts
+#undef  LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL
+#define LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL hook_bool_const_tree_false
 
 struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;