block/nfs: add missing #include "qapi/error.h"

error_setg() used to be included indirectly through qemu/osdep.h.  Since
commit da34e65 ("include/qemu/osdep.h:
Don't include qapi/error.h") it requires an explicit include.

Cc: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1459341994-20567-2-git-send-email-stefanha@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>

block/nfs.c

@@ -28,6 +28,7 @@
 #include "qemu-common.h"
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
+#include "qapi/error.h"
 #include "block/block_int.h"
 #include "trace.h"
 #include "qemu/iov.h"