Circumvent ASAN false positive

Summary:
Changes:
* checks if ASAN mode is on, and uses malloc and free in the constructor and destructor
Closes https://github.com/facebook/rocksdb/pull/2767

Differential Revision: D5671243

Pulled By: armishra

fbshipit-source-id: 8e4ad0f7f163400c4effa8617d3b30134119d802

cache/lru_cache.cc

@@ -234,19 +234,35 @@ void LRUCacheShard::EvictFromLRU(size_t charge,
 }
 
 void* LRUCacheShard::operator new(size_t size) {
+#if __SANITIZE_ADDRESS__
+  return malloc(size);
+#else
   return port::cacheline_aligned_alloc(size);
+#endif
 }
 
 void* LRUCacheShard::operator new[](size_t size) {
+#if __SANITIZE_ADDRESS__
+  return malloc(size);
+#else
   return port::cacheline_aligned_alloc(size);
+#endif
 }
 
 void LRUCacheShard::operator delete(void *memblock) {
+#if __SANITIZE_ADDRESS__
+  free(memblock);
+#else
   port::cacheline_aligned_free(memblock);
+#endif
 }
 
 void LRUCacheShard::operator delete[](void* memblock) {
+#if __SANITIZE_ADDRESS__
+  free(memblock);
+#else
   port::cacheline_aligned_free(memblock);
+#endif
 }
 
 void LRUCacheShard::SetCapacity(size_t capacity) {