CYGWIN: GCC prints "defined but not used" warnings on mimalloc

Bug report

Bug description:

Compiling under CYGWIN prints these warning messages:

In file included from ../cpython/Objects/mimalloc/prim/prim.c:22,
                 from ../cpython/Objects/mimalloc/static.c:37,
                 from ../cpython/Objects/obmalloc.c:23:
../cpython/Objects/mimalloc/prim/unix/prim.c:91:12: warning: ‘mi_prim_access’ defined but not used [-Wunused-function]
   91 | static int mi_prim_access(const char *fpath, int mode) {
      |            ^~~~~~~~~~~~~~
../cpython/Objects/mimalloc/prim/unix/prim.c:88:12: warning: ‘mi_prim_close’ defined but not used [-Wunused-function]
   88 | static int mi_prim_close(int fd) {
      |            ^~~~~~~~~~~~~
../cpython/Objects/mimalloc/prim/unix/prim.c:85:16: warning: ‘mi_prim_read’ defined but not used [-Wunused-function]
   85 | static ssize_t mi_prim_read(int fd, void* buf, size_t bufsize) {
      |                ^~~~~~~~~~~~
../cpython/Objects/mimalloc/prim/unix/prim.c:82:12: warning: ‘mi_prim_open’ defined but not used [-Wunused-function]
   82 | static int mi_prim_open(const char* fpath, int open_flags) {
      |            ^~~~~~~~~~~~

Looking into the code of Objects/mimalloc/prim/unix/prim.c, there is already a conditional block to avoid the generation of such warnings.
The solution for this issue is to simply add CYGWIN to that list of platforms.
So, I'm posting this issue according to the suggestion received into #146572 for tracking this change.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

• gh-146599

Comece em Objects/mimalloc/prim/unix/prim.c e inspecione o bloco condicional existente destinado a suprimir avisos sobre funções não utilizadas em plataformas selecionadas. Verifique a lista de plataformas e faça um build do Cygwin para confirmar que os quatro avisos não aparecem mais; o PR vinculado gh-146599 indica que o trabalho já está em andamento.