block/raw-posix: Make hdev_aio_discard() available outside Linux

Fixes the build on OpenBSD among others.
Suggested-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAndreas Färber <andreas.faerber@web.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

block/raw-posix.c

@@ -1371,19 +1371,6 @@ static BlockDriverAIOCB *hdev_aio_ioctl(BlockDriverState *bs,
     return thread_pool_submit_aio(aio_worker, acb, cb, opaque);
 }
 
-static coroutine_fn BlockDriverAIOCB *hdev_aio_discard(BlockDriverState *bs,
-    int64_t sector_num, int nb_sectors,
-    BlockDriverCompletionFunc *cb, void *opaque)
-{
-    BDRVRawState *s = bs->opaque;
-
-    if (fd_open(bs) < 0) {
-        return NULL;
-    }
-    return paio_submit(bs, s->fd, sector_num, NULL, nb_sectors,
-                       cb, opaque, QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);
-}
-
 #elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 static int fd_open(BlockDriverState *bs)
 {
@@ -1403,6 +1390,19 @@ static int fd_open(BlockDriverState *bs)
 
 #endif /* !linux && !FreeBSD */
 
+static coroutine_fn BlockDriverAIOCB *hdev_aio_discard(BlockDriverState *bs,
+    int64_t sector_num, int nb_sectors,
+    BlockDriverCompletionFunc *cb, void *opaque)
+{
+    BDRVRawState *s = bs->opaque;
+
+    if (fd_open(bs) < 0) {
+        return NULL;
+    }
+    return paio_submit(bs, s->fd, sector_num, NULL, nb_sectors,
+                       cb, opaque, QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);
+}
+
 static int hdev_create(const char *filename, QEMUOptionParameter *options)
 {
     int fd;