GH-47475: [C++] Bump vendored xxhash to 0.8.3

Author: raulcd

cpp/src/arrow/vendored/xxhash/README.md

@@ -17,5 +17,5 @@
   under the License.
 -->
 
-The files in this directory are vendored from xxHash git tag v0.8.2
+The files in this directory are vendored from xxHash git tag v0.8.3
 (https://github.com/Cyan4973/xxHash).

cpp/src/arrow/vendored/xxhash/xxhash.c

@@ -1,6 +1,6 @@
 /*
  * xxHash - Extremely Fast Hash algorithm
- * Copyright (C) 2012-2021 Yann Collet
+ * Copyright (C) 2012-2023 Yann Collet
  *
  * BSD 2-Clause License (https://www.opensource.org/licenses/bsd-license.php)
  *
@@ -32,12 +32,11 @@
  *   - xxHash source repository: https://github.com/Cyan4973/xxHash
  */
 
-
 /*
  * xxhash.c instantiates functions defined in xxhash.h
  */
 
-#define XXH_STATIC_LINKING_ONLY   /* access advanced declarations */
-#define XXH_IMPLEMENTATION   /* access definitions */
+#define XXH_STATIC_LINKING_ONLY /* access advanced declarations */
+#define XXH_IMPLEMENTATION      /* access definitions */
 
 #include "xxhash.h"