Separate Malloc and MemMap ArenaPools

Make ArenaPool an abstract base class and leave MallocArenaPool
implementation with it.  This enables arena_allocator to be free
of MemMap, Mutex, etc., in preparation to move the remaining collections
out of runtime/base to libartbase/base.

Bug: 22322814
Test: make -j 50 test-art-host
      build and boot

Change-Id: Ief84dcbfb749165d9bc82000c6b8f96f93052422
diff --git a/compiler/utils/assembler_test.h b/compiler/utils/assembler_test.h
index 0cb8bbb..7c800b3 100644
--- a/compiler/utils/assembler_test.h
+++ b/compiler/utils/assembler_test.h
@@ -26,6 +26,7 @@
 #include <fstream>
 #include <iterator>
 
+#include "base/malloc_arena_pool.h"
 #include "assembler_test_base.h"
 #include "common_runtime_test.h"  // For ScratchFile
 
@@ -1606,7 +1607,7 @@
 
   static constexpr size_t kWarnManyCombinationsThreshold = 500;
 
-  ArenaPool pool_;
+  MallocArenaPool pool_;
   std::unique_ptr<ArenaAllocator> allocator_;
   std::unique_ptr<Ass> assembler_;
   std::unique_ptr<AssemblerTestInfrastructure> test_helper_;