os: Define {ReadFdFrom,WriteFdTo}Client unconditionally

Otherwise this is broken on cygwin:

    rrlease.c: In function ‘ProcRRCreateLease’:
    rrlease.c:305:9: error: implicit declaration of function ‘WriteFdToClient’ [-Werror=implicit-function-declaration]
         if (WriteFdToClient(client, fd, TRUE) < 0) {

Signed-off-by: Adam Jackson <ajax@redhat.com>

include/dixstruct.h

@@ -113,14 +113,12 @@ typedef struct _Client {
     int req_fds;
 } ClientRec;
 
-#if XTRANS_SEND_FDS
 static inline void
 SetReqFds(ClientPtr client, int req_fds) {
     if (client->req_fds != 0 && req_fds != client->req_fds)
         LogMessage(X_ERROR, "Mismatching number of request fds %d != %d\n", req_fds, client->req_fds);
     client->req_fds = req_fds;
 }
-#endif
 
 /*
  * Scheduling interface

include/os.h

@@ -106,11 +106,9 @@ extern _X_EXPORT Bool WaitForSomething(Bool clients_are_ready);
 
 extern _X_EXPORT int ReadRequestFromClient(ClientPtr /*client */ );
 
-#if XTRANS_SEND_FDS
 extern _X_EXPORT int ReadFdFromClient(ClientPtr client);
 
 extern _X_EXPORT int WriteFdToClient(ClientPtr client, int fd, Bool do_close);
-#endif
 
 extern _X_EXPORT Bool InsertFakeRequest(ClientPtr /*client */ ,
                                         char * /*data */ ,

os/io.c

@@ -464,12 +464,12 @@ ReadRequestFromClient(ClientPtr client)
     return needed;
 }
 
-#if XTRANS_SEND_FDS
 int
 ReadFdFromClient(ClientPtr client)
 {
     int fd = -1;
 
+#if XTRANS_SEND_FDS
     if (client->req_fds > 0) {
         OsCommPtr oc = (OsCommPtr) client->osPrivate;
 
@@ -477,17 +477,22 @@ ReadFdFromClient(ClientPtr client)
         fd = _XSERVTransRecvFd(oc->trans_conn);
     } else
         LogMessage(X_ERROR, "Request asks for FD without setting req_fds\n");
+#endif
+
     return fd;
 }
 
 int
 WriteFdToClient(ClientPtr client, int fd, Bool do_close)
 {
+#if XTRANS_SEND_FDS
     OsCommPtr oc = (OsCommPtr) client->osPrivate;
 
     return _XSERVTransSendFd(oc->trans_conn, fd, do_close);
-}
+#else
+    return -1;
 #endif
+}
 
 /*****************************************************************
  * InsertFakeRequest