Use 'final' and 'override' specifiers directly in ART.

Remove all uses of macros 'FINAL' and 'OVERRIDE' and replace them with
'final' and 'override' specifiers. Remove all definitions of these
macros as well, which were located in these files:
- libartbase/base/macros.h
- test/913-heaps/heaps.cc
- test/ti-agent/ti_macros.h

ART is now using C++14; the 'final' and 'override' specifiers have
been introduced in C++11.

Test: mmma art
Change-Id: I256c7758155a71a2940ef2574925a44076feeebf
diff --git a/libartbase/base/allocator.cc b/libartbase/base/allocator.cc
index c4ac180..1bcfe87 100644
--- a/libartbase/base/allocator.cc
+++ b/libartbase/base/allocator.cc
@@ -25,7 +25,7 @@
 
 namespace art {
 
-class MallocAllocator FINAL : public Allocator {
+class MallocAllocator final : public Allocator {
  public:
   MallocAllocator() {}
   ~MallocAllocator() {}
@@ -44,7 +44,7 @@
 
 MallocAllocator g_malloc_allocator;
 
-class NoopAllocator FINAL : public Allocator {
+class NoopAllocator final : public Allocator {
  public:
   NoopAllocator() {}
   ~NoopAllocator() {}