Making the hashing buffer reusable instead of malloc every file

binaries/changelog.txt

@@ -7,7 +7,6 @@ v2.0: Multi threaded scan
 v2.1: Uses AVX2 instead of SSE2
 
 v3.0: Simple mutex/critical section based MPMC queue
-reusable hashing buffer
 
 v3.1: Lock free MPMC queue Vyukov-style
 
@@ -22,5 +21,7 @@ Reorder helper functions
 v3.4: Rewriting hash_worker() to export file_hashes.txt
 
 v4.0: Instead of writing directly to file_hashes.txt, hash_workers now are using a local arena, writing everything once at the end
-using #pragma once to ensure that a given header file is included only once in a single compilation unit
-forcing xxhash to use the stack instead of the heap
+Using #pragma once to ensure that a given header file is included only once in a single compilation unit
+Forcing xxhash to use the stack instead of the heap
+Making the hashing buffer reusable instead of malloc every file
+Implementing a general purpose arena to replace small allocations