libgolang/gevent: Adjust to support Windows

On Windows rthere is no fcntl

    golang/runtime\_runtime_gevent.cpp(4811): error C3861: 'S_ISBLK': identifier not found
    golang/runtime\_runtime_gevent.cpp(4823): error C2039: 'Fcntl': is not a member of 'golang::internal::syscall'
    .\golang/runtime/internal/syscall.h(36): note: see declaration of 'golang::internal::syscall'
    golang/runtime\_runtime_gevent.cpp(4823): error C2065: 'F_GETFL': undeclared identifier
    golang/runtime\_runtime_gevent.cpp(4823): error C3861: 'Fcntl': identifier not found
    golang/runtime\_runtime_gevent.cpp(4870): error C2065: 'O_ACCMODE': undeclared identifier
    golang/runtime\_runtime_gevent.cpp(4889): error C2039: 'Fcntl': is not a member of 'golang::internal::syscall'
    .\golang/runtime/internal/syscall.h(36): note: see declaration of 'golang::internal::syscall'
    golang/runtime\_runtime_gevent.cpp(4889): error C2065: 'F_SETFL': undeclared identifier
    golang/runtime\_runtime_gevent.cpp(4889): error C2065: 'O_NONBLOCK': undeclared identifier
    golang/runtime\_runtime_gevent.cpp(4889): error C3861: 'Fcntl': identifier not found

and even if there would be gevent does not provide cooperative version
of FileObject for non-POSIX platforms.

-> Always use FileObjectThread on windows even for pipes.

golang/runtime/_runtime_gevent.pyx

 # cython: language_level=2
-# Copyright (C) 2019-2022  Nexedi SA and Contributors.
+# Copyright (C) 2019-2023  Nexedi SA and Contributors.
 #                          Kirill Smelkov <kirr@nexedi.com>
 #
 # This program is free software: you can Use, Study, Modify and Redistribute
@@ -57,7 +57,7 @@ from posix.fcntl cimport mode_t, F_GETFL, F_SETFL, O_NONBLOCK, O_ACCMODE, O_RDON
 from posix.stat cimport struct_stat, S_ISREG, S_ISDIR, S_ISBLK
 from posix.strings cimport bzero
 
-from gevent.fileobject import FileObjectThread, FileObjectPosix
+from gevent import fileobject as gfileobj
 
 
 # _goviapy & _togo serve go
@@ -194,31 +194,39 @@ cdef nogil:
         return ioh
 
     _libgolang_ioh* _io_fdopen(int *out_syserr, int sysfd):
-        # check if we should enable O_NONBLOCK on this file-descriptor
-        # even though we could enable O_NONBLOCK for regular files, it does not
-        # work as expected as most unix'es report regular files as always read
-        # and write ready.
-        cdef struct_stat st
-        cdef int syserr = syscall.Fstat(sysfd, &st)
-        if syserr < 0:
-            out_syserr[0] = syserr
-            return NULL
-        m = st.st_mode
-        blocking = (S_ISREG(m) or S_ISDIR(m) or S_ISBLK(m)) # fd cannot refer to symlink
-
-        # retrieve current sysfd flags and access mode
-        flags = syscall.Fcntl(sysfd, F_GETFL, 0)
-        if flags < 0:
-            out_syserr[0] = flags
-            return NULL
-        acc = (flags & O_ACCMODE)
-
-        # enable O_NONBLOCK if needed
-        if not blocking:
-            syserr = syscall.Fcntl(sysfd, F_SETFL, flags | O_NONBLOCK)
+        IF POSIX:
+            # check if we should enable O_NONBLOCK on this file-descriptor
+            # even though we could enable O_NONBLOCK for regular files, it does not
+            # work as expected as most unix'es report regular files as always read
+            # and write ready.
+            cdef struct_stat st
+            cdef int syserr = syscall.Fstat(sysfd, &st)
             if syserr < 0:
                 out_syserr[0] = syserr
                 return NULL
+            m = st.st_mode
+            blocking = (S_ISREG(m) or S_ISDIR(m) or S_ISBLK(m)) # fd cannot refer to symlink
+
+            # retrieve current sysfd flags and access mode
+            flags = syscall.Fcntl(sysfd, F_GETFL, 0)
+            if flags < 0:
+                out_syserr[0] = flags
+                return NULL
+            acc = (flags & O_ACCMODE)
+
+            # enable O_NONBLOCK if needed
+            if not blocking:
+                syserr = syscall.Fcntl(sysfd, F_SETFL, flags | O_NONBLOCK)
+                if syserr < 0:
+                    out_syserr[0] = syserr
+                    return NULL
+
+        ELSE: # !POSIX (windows)
+            cdef bint blocking = True
+            # FIXME acc: use GetFileInformationByHandleEx to determine whether
+            # HANDLE(sysfd) was opened for reading or writing.
+            # https://stackoverflow.com/q/9442436/9456786
+            cdef int acc = O_RDWR
 
         # create IOH backed by FileObjectThread or FileObjectPosix
         ioh = <IOH*>calloc(1, sizeof(IOH))
@@ -253,9 +261,9 @@ cdef:
         pygfobj = None
         try:
             if blocking:
-                pygfobj = FileObjectThread(sysfd, mode=mode, buffering=0)
+                pygfobj = gfileobj.FileObjectThread(sysfd, mode=mode, buffering=0)
             else:
-                pygfobj = FileObjectPosix(sysfd, mode=mode, buffering=0)
+                pygfobj = gfileobj.FileObjectPosix(sysfd, mode=mode, buffering=0)
         except OSError as e:
             out_syserr[0] = -e.errno
         else: