[Allocator] Nuke to useless functions. The implicit ones are sufficient

here (obviously).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206369 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Allocator.h

@@ -94,9 +94,6 @@ public:
 
 class MallocAllocator : public AllocatorBase<MallocAllocator> {
 public:
-  MallocAllocator() {}
-  ~MallocAllocator() {}
-
   void Reset() {}
 
   void *Allocate(size_t Size, size_t /*Alignment*/) { return malloc(Size); }