Fix all our unused parameter warnings so we let GCC report them.

There were a couple of genuine bugs here (fixed), plus there's a missing
feature in trace.cc that I've just added a TODO for.

Also note that I haven't touched the compilers; this warning is still
explicitly disabled for that code. I'll do that when there's less going
on in those directories.

Change-Id: Ic3570bf82411a07c7530bfaf1995ac995b9fc00f
diff --git a/src/runtime_support.cc b/src/runtime_support.cc
index 1828985..230c24f 100644
--- a/src/runtime_support.cc
+++ b/src/runtime_support.cc
@@ -208,7 +208,7 @@
   thread->DeliverException();
 }
 
-extern "C" void artThrowStackOverflowFromCode(Method* method, Thread* thread, Method** sp) {
+extern "C" void artThrowStackOverflowFromCode(Method* /*method*/, Thread* thread, Method** sp) {
   FinishCalleeSaveFrameSetup(thread, sp, Runtime::kSaveAll);
   // Remove extra entry pushed onto second stack during method tracing
   if (Runtime::Current()->IsMethodTracingActive()) {