[runtime] Don't prepend '0x' to %p-formatted numbers.

%p-formatted numbers already include '0x'

Fixes this output when dumping threads:

    "Threadpool worker" tid=0x0x7000105cc000 this=0x0x10bc18508 , thread handle : 0x7fbb9e6c6c90, state : not waiting

to become:

    "Threadpool worker" tid=0x7000105cc000 this=0x10bc18508 , thread handle : 0x7fbb9e6c6c90, state : not waiting


Commit migrated from mono/mono@481827b

src/mono/mono/mini/mini-exceptions.c

@@ -2808,7 +2808,7 @@ mono_print_thread_dump_internal (void *sigctx, MonoContext *start_ctx)
 	else
 		g_string_append (text, "\n\"<unnamed thread>\"");
 
-	g_string_append_printf (text, " tid=0x%p this=0x%p ", (gpointer)(gsize)thread->tid, thread);
+	g_string_append_printf (text, " tid=%p this=%p ", (gpointer)(gsize)thread->tid, thread);
 	mono_thread_internal_describe (thread, text);
 	g_string_append (text, "\n");