fix(math): correct xvec calculation in vm_vector_2_matrix_gen_vectors#7162

BMagnu merged 1 commit intoscp-fs2open:masterscp-fs2open/fs2open.github.com:masterfrom

danielchristiancazares:fix/xvec-calculationdanielchristiancazares/fs2open.github.com:fix/xvec-calculationCopy head branch name to clipboard