Fix from Lawrence Mulholland (NAG).

Fix from Lawrence Mulholland (NAG).

From Lawrence:
	The *GEQRT routines are supposed to return immediately when N=0 or M=0.
	However the code is such that an INFO = -3 is triggered since we are
	trying to satisfy
		ELSE IF( NB.LT.1 .OR. NB.GT.MIN(M,N) )THEN
			INFO = -3
	should be
		ELSE IF( NB.LT.1 .OR. ( NB.GT.MIN(M,N) .AND. MIN(M,N).LT.0 ) )THEN
			INFO = -3

Also on a side note, I think we could allow NB to be greater than MIN(M,N) in
the interface and then reset NB as needed if the user's NB is too large.
Another day. Good enough for now.

Julien.