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/arch/x86/context_x86.cc b/runtime/arch/x86/context_x86.cc
index 32eec57..49aa326 100644
--- a/runtime/arch/x86/context_x86.cc
+++ b/runtime/arch/x86/context_x86.cc
@@ -72,6 +72,16 @@
   }
 }
 
+bool X86Context::GetFPR(uint32_t reg ATTRIBUTE_UNUSED, uintptr_t* val ATTRIBUTE_UNUSED) {
+  LOG(FATAL) << "Floating-point registers are all caller save in X86";
+  UNREACHABLE();
+}
+
+bool X86Context::SetFPR(uint32_t reg ATTRIBUTE_UNUSED, uintptr_t value ATTRIBUTE_UNUSED) {
+  LOG(FATAL) << "Floating-point registers are all caller save in X86";
+  UNREACHABLE();
+}
+
 void X86Context::DoLongJump() {
 #if defined(__i386__)
   // Array of GPR values, filled from the context backward for the long jump pop. We add a slot at