Fix nanmax and nanmin behavior on empty arrays to match MATLAB

[Sonu0305]

Before (Octave):

>> nanmax([])
   NaN
## Size: [1 1]

>> nanmax(ones(2, 0, 3, 2), [], 2)
error: Invalid resizing operation or ambiguous assignment to an out-of-bounds array element

After (Octave) & MATLAB Expected Behavior:

>> nanmax([])
## Size: [0 0]

>> nanmax(ones(2, 0, 3, 2), [], 2)
## Size: [2 0 3 2] empty array