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/compiler/utils/arm/assembler_arm32.cc b/compiler/utils/arm/assembler_arm32.cc
index d262b6a..c8a57b1 100644
--- a/compiler/utils/arm/assembler_arm32.cc
+++ b/compiler/utils/arm/assembler_arm32.cc
@@ -1303,7 +1303,6 @@
   }
 }
 
-
 void Arm32Assembler::LoadImmediate(Register rd, int32_t value, Condition cond) {
   ShifterOperand shifter_op;
   if (ShifterOperand::CanHoldArm(value, &shifter_op)) {
@@ -1483,12 +1482,12 @@
 }
 
 
-void Arm32Assembler::cbz(Register rn, Label* target) {
+void Arm32Assembler::cbz(Register rn ATTRIBUTE_UNUSED, Label* target ATTRIBUTE_UNUSED) {
   LOG(FATAL) << "cbz is not supported on ARM32";
 }
 
 
-void Arm32Assembler::cbnz(Register rn, Label* target) {
+void Arm32Assembler::cbnz(Register rn ATTRIBUTE_UNUSED, Label* target ATTRIBUTE_UNUSED) {
   LOG(FATAL) << "cbnz is not supported on ARM32";
 }