io.c: Avoid warnings when building without logging

Follow-up of commit 057ae26

References libusb#1508
Fixes libusb#1630
Closes libusb#1752

Signed-off-by: Tormod Volden <debian.tormod@gmail.com>

Author: tormodvolden

libusb/io.c

@@ -1370,8 +1370,10 @@ static int arm_timer_for_next_timeout(struct libusb_context *ctx)
 
 		/* act on first transfer that has not already been handled */
 		if (!(itransfer->timeout_flags & (USBI_TRANSFER_TIMEOUT_HANDLED | USBI_TRANSFER_OS_HANDLES_TIMEOUT))) {
+#ifdef ENABLE_LOGGING
 			struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 			usbi_dbg(ctx, "next timeout originally %ums", transfer->timeout);
+#endif
 			return usbi_arm_timer(&ctx->timer, cur_ts);
 		}
 	}
@@ -1434,9 +1436,11 @@ static int add_to_flying_list(struct usbi_transfer *itransfer)
 	if (first && usbi_using_timer(ctx) && TIMESPEC_IS_SET(timeout)) {
 		/* if this transfer has the lowest timeout of all active transfers,
 		 * rearm the timer with this transfer's timeout */
+#ifdef ENABLE_LOGGING
 		struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 		usbi_dbg(ctx, "arm timer for timeout in %ums (first in line)",
 			transfer->timeout);
+#endif
 		r = usbi_arm_timer(&ctx->timer, timeout);
 	}
 #else