Fix some function pointer types to match, i.e. so C++ compiles w/o extra casts. (mono#6732)

Author: jaykrell

mono/metadata/boehm-gc.c

@@ -1483,7 +1483,7 @@ void mono_gc_set_skip_thread (gboolean value)
 }
 
 void
-mono_gc_register_for_finalization (MonoObject *obj, void *user_data)
+mono_gc_register_for_finalization (MonoObject *obj, MonoFinalizationProc user_data)
 {
 	guint offset = 0;
 

mono/metadata/gc-internals.h

@@ -140,7 +140,9 @@ MonoGCDescriptor mono_gc_make_descr_for_string (gsize *bitmap, int numbits);
 
 void mono_gc_register_obj_with_weak_fields (void *obj);
 
-void  mono_gc_register_for_finalization (MonoObject *obj, void *user_data);
+typedef void (*MonoFinalizationProc)(gpointer, gpointer); // same as SGenFinalizationProc, GC_finalization_proc
+
+void  mono_gc_register_for_finalization (MonoObject *obj, MonoFinalizationProc user_data);
 void  mono_gc_add_memory_pressure (gint64 value);
 MONO_API int   mono_gc_register_root (char *start, size_t size, MonoGCDescriptor descr, MonoGCRootSource source, void *key, const char *msg);
 void  mono_gc_deregister_root (char* addr);

mono/metadata/sgen-mono.c

@@ -545,7 +545,7 @@ sgen_client_finalize_notify (void)
 }
 
 void
-mono_gc_register_for_finalization (MonoObject *obj, void *user_data)
+mono_gc_register_for_finalization (MonoObject *obj, MonoFinalizationProc user_data)
 {
 	sgen_object_register_for_finalization (obj, user_data);
 }

mono/sgen/sgen-fin-weak-hash.c

@@ -548,7 +548,7 @@ sgen_process_fin_stage_entries (void)
 }
 
 void
-sgen_object_register_for_finalization (GCObject *obj, void *user_data)
+sgen_object_register_for_finalization (GCObject *obj, SGenFinalizationProc user_data)
 {
 	while (add_stage_entry (NUM_FIN_STAGE_ENTRIES, &next_fin_stage_entry, fin_stage_entries, obj, user_data) == -1) {
 		if (try_lock_stage_for_processing (NUM_FIN_STAGE_ENTRIES, &next_fin_stage_entry)) {

mono/sgen/sgen-gc.h

@@ -827,7 +827,10 @@ void sgen_null_link_in_range (int generation, ScanCopyContext ctx, gboolean trac
 void sgen_process_fin_stage_entries (void)
 	MONO_PERMIT (need (sgen_gc_locked));
 gboolean sgen_have_pending_finalizers (void);
-void sgen_object_register_for_finalization (GCObject *obj, void *user_data)
+
+typedef void (*SGenFinalizationProc)(gpointer, gpointer); // same as MonoFinalizationProc, GC_finalization_proc
+
+void sgen_object_register_for_finalization (GCObject *obj, SGenFinalizationProc user_data)
 	MONO_PERMIT (need (sgen_lock_gc));
 
 void sgen_finalize_if (SgenObjectPredicateFunc predicate, void *user_data)