Add benchmarks for special matrices

[YingboMa]

Aside from the differences of BLAS and LAPACK in Julia and Matlab, it maybe meaningful to compare the algorithms between Julia and Matlab. For instance, sqrtm function requires to do a Schur decomposition for a normal square matrix which highly depends on LAPACK. How about benchmark sqrtm for an upper triangular matrix?

[RoyiAvital]

I will soon have MATLAB R2017a.
I intend to re run the benchmark then.

I will add your suggestion as a new test.