ART: Fix "unused parameters"

GCC 4.8 decides that parameters for functions implemented with
"= default" are unused. This currently only impacts x86, but remove
the parameter names anyways.

Change-Id: I01865faa81af68c4c0e0b1cb1fb19e88ef548769
diff --git a/runtime/base/scoped_arena_containers.h b/runtime/base/scoped_arena_containers.h
index 664a909..df79085 100644
--- a/runtime/base/scoped_arena_containers.h
+++ b/runtime/base/scoped_arena_containers.h
@@ -85,8 +85,8 @@
         ArenaAllocatorAdapterKind(other),
         arena_stack_(other.arena_stack_) {
   }
-  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter& other) = default;
-  ScopedArenaAllocatorAdapter& operator=(const ScopedArenaAllocatorAdapter& other) = default;
+  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter&) = default;
+  ScopedArenaAllocatorAdapter& operator=(const ScopedArenaAllocatorAdapter&) = default;
   ~ScopedArenaAllocatorAdapter() = default;
 
  private:
@@ -128,8 +128,8 @@
         ArenaAllocatorAdapterKind(other),
         arena_stack_(other.arena_stack_) {
   }
-  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter& other) = default;
-  ScopedArenaAllocatorAdapter& operator=(const ScopedArenaAllocatorAdapter& other) = default;
+  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter&) = default;
+  ScopedArenaAllocatorAdapter& operator=(const ScopedArenaAllocatorAdapter&) = default;
   ~ScopedArenaAllocatorAdapter() = default;
 
   size_type max_size() const {