More extended performance profiling

[Rik]

I was able to get versions 3.2.4 and 4.0.3 to compile so I have a longer baseline of performance measurements.  Using bm_toeplitz.m, there has been more than 100% slowdown since 3.2.4 to current dev.

Version	3.2.4	3.4.3	3.6.4	3.8.2	4.0.3	4.2.1	4.4.1	5.1.0	dev (6.1.0)
runtime	5.8968				10.055	10.544	13.052	13.481	13.291

--Rik