[3.13] gh-121731: Fix mimalloc compile error on GNU/Hurd (GH-121732) (#121773)

(cherry picked from commit d005f2c)

Co-authored-by: Samuel Thibault <[email protected]>

Author: miss-islington

Misc/NEWS.d/next/Build/2024-07-14-01-29-47.gh-issue-121731.RMPGP3.rst

@@ -0,0 +1 @@
+Fix mimalloc compile error on GNU/Hurd

Objects/mimalloc/prim/unix/prim.c

@@ -27,6 +27,7 @@ terms of the MIT license. A copy of the license can be found in the file
 
 #include <sys/mman.h>  // mmap
 #include <unistd.h>    // sysconf
+#include <fcntl.h>     // open, close, read, access
 
 #if defined(__linux__)
   #include <features.h>