fixup! mimalloc: adjust for building inside Git

Revert this in preparation for upgrading mimalloc to v2.1.2 and then
redoing this patch.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

compat/mimalloc/alloc.c

@@ -16,6 +16,10 @@ terms of the MIT license. A copy of the license can be found in the file
 #include <string.h>  // memset, strlen
 #include <stdlib.h>  // malloc, exit
 
+#define MI_IN_ALLOC_C
+#include "alloc-override.c"
+#undef MI_IN_ALLOC_C
+
 // ------------------------------------------------------
 // Allocation
 // ------------------------------------------------------

compat/mimalloc/mimalloc.h

@@ -95,8 +95,7 @@ terms of the MIT license. A copy of the license can be found in the file
 // Includes
 // ------------------------------------------------------
 
-#include "git-compat-util.h"
-
+#include <stddef.h>     // size_t
 #include <stdbool.h>    // bool
 #include <stdint.h>     // INTPTR_MAX