## Logic for detection of bitwidth (32 or 64) for x13as binary is incorrect

The function `src/utilities/is/is64bit.m`

is used to decide whether we use a 32-bit or 64-bit binary of x13as.

The logic of this test is doubly wrong.

First, it claims to check whether MATLAB or Octave is 32-bit or 64-bit, but it does it by checking the maximum size of matrix indices (there are 64-bit version of Octave which have a 32-bit index).

But, fundamentally, testing the bitwidth of MATLAB/Octave is not what we want, since x13as is an independent executable. We should rather test whether the operating system is 32- or 64-bit, as is currently done for the preprocessor binary.