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/stack.h b/runtime/stack.h
index 2f8df61..66c840d 100644
--- a/runtime/stack.h
+++ b/runtime/stack.h
@@ -53,6 +53,7 @@
   kImpreciseConstant,
   kUndefined,
 };
+std::ostream& operator<<(std::ostream& os, const VRegKind& rhs);
 
 // A reference from the shadow stack to a MirrorType object within the Java heap.
 template<class MirrorType>
@@ -336,9 +337,7 @@
   }
 
 #if defined(ART_USE_PORTABLE_COMPILER)
-  enum ShadowFrameFlag {
-    kHasReferenceArray = 1ul << 31
-  };
+  constexpr uint32_t kHasReferenceArray = 1ul << 31;
   // TODO: make const in the portable case.
   uint32_t number_of_vregs_;
 #else
@@ -633,6 +632,7 @@
   }
 
   static int GetOutVROffset(uint16_t out_num, InstructionSet isa) {
+    UNUSED(isa);
     // According to stack model, the first out is above the Method referernce.
     return sizeof(StackReference<mirror::ArtMethod>) + (out_num * sizeof(uint32_t));
   }