Add IEEE code for Aarch64 in libgfortran

[fxcoudert]

Fixes #8

[iains]

thanks!

[fxcoudert]

🚀

$ cat a.f90
  use, intrinsic :: ieee_exceptions
  use, intrinsic :: ieee_arithmetic
  implicit none
  real :: x

  type(ieee_round_type) r
  call ieee_get_rounding_mode(r)
  if (r == ieee_nearest) print *, 'Rounding to nearest'
  x = 9
  print *, 1/x
  call ieee_set_rounding_mode(ieee_up)
  x = 9
  print *, 1/x
  call ieee_set_rounding_mode(ieee_down)
  x = 9
  print *, 1/x
  call ieee_get_rounding_mode(r)
  if (r == ieee_nearest) print *, 'Rounding to nearest'
  if (r == ieee_down) print *, 'Rounding down'
  end
$ ./bin/gfortran a.f90 && ./a.out
 Rounding to nearest
  0.111111112    
  0.111111112    
  0.111111104    
 Rounding down