Branch b1_4

Branch b1_4
Description: if client is started with down MDS mount hangs in ptlrpc_queue_wait
Details    : Having an LWI_INTR() wait event (interruptible, but no timeout)
	     will wait indefinitely in ptlrpc_queue_wait->l_wait_event() after
	     ptlrpc_import_delayed_req() because we didn't check if the
	     request was interrupted, and we also didn't break out of the
	     event loop if there was no timeout.

__l_wait_event() changes match those recently made in HEAD.
b=7184
r=devesh