Change default JIT code buffer size to 16kb

Few cores have that big an L1I cache.

PiperOrigin-RevId: 421670023
diff --git a/src/xnnpack/allocator.h b/src/xnnpack/allocator.h
index 78ff0bf..be67dd9 100644
--- a/src/xnnpack/allocator.h
+++ b/src/xnnpack/allocator.h
@@ -87,7 +87,7 @@
     ((void*) ((((uintptr_t) alloca((size) + XNN_ALLOCATION_ALIGNMENT)) | (XNN_ALLOCATION_ALIGNMENT - 1)) + 1))
 #endif
 
-#define XNN_DEFAULT_CODE_BUFFER_SIZE 131072  // 128kb.
+#define XNN_DEFAULT_CODE_BUFFER_SIZE 16384  // 16kb.
 
 #ifdef __cplusplus
 extern "C" {