Remove vcl_math calls

Remove vcl_math calls

In the early days of itk development, many c++ compilers treated
math functions inconsistently. The vcl_math routines provided a
platform independent interface. Now, with modern c++ compilers, math
functions are treated more uniformly. This patch removes the vcl_math
calls. The extra layer provided by vcl is no longer needed and may
even cause problems with newer compilers.