Remove -Wno-unused-parameter and -Wno-sign-promo from base cflags.

Fix associated errors about unused paramenters and implict sign conversions.
For sign conversion this was largely in the area of enums, so add ostream
operators for the effected enums and fix tools/generate-operator-out.py.
Tidy arena allocation code and arena allocated data types, rather than fixing
new and delete operators.
Remove dead code.

Change-Id: I5b433e722d2f75baacfacae4d32aef4a828bfe1b
diff --git a/runtime/noop_compiler_callbacks.h b/runtime/noop_compiler_callbacks.h
index e9ad353..300abc9 100644
--- a/runtime/noop_compiler_callbacks.h
+++ b/runtime/noop_compiler_callbacks.h
@@ -26,11 +26,11 @@
   NoopCompilerCallbacks() {}
   ~NoopCompilerCallbacks() {}
 
-  bool MethodVerified(verifier::MethodVerifier* verifier) OVERRIDE {
+  bool MethodVerified(verifier::MethodVerifier* verifier ATTRIBUTE_UNUSED) OVERRIDE {
     return true;
   }
 
-  void ClassRejected(ClassReference ref) OVERRIDE {}
+  void ClassRejected(ClassReference ref ATTRIBUTE_UNUSED) OVERRIDE {}
 
   // This is only used by compilers which need to be able to run without relocation even when it
   // would normally be enabled. For example the patchoat executable, and dex2oat --image, both need