Propose to XFAIL tests on ppc64

[Jerry DeLisle]

Testing on ppc64 Linux system:

Using:

program elarge
   integer, parameter :: k = 16
   real(kind=k) :: a,b(2)
   character(len=380) :: tmp
   b(:) = huge(0.0_k)
   write (tmp,'(2(1x,g60.52))') b(1)
   read (tmp, *) a
   print '(a)', "01234567890123456789012345678901234567890123456789"
   print '(a)', trim(tmp)
   print '(1p,g60.52)', b(1)
   print '(1p,g60.52)', a
   print *, a
   print '(1p,g60.52)', a-b(1)
   if (a /= b(1)) print *, "no match"
end program elarge

Gives:

  $ ./a.out
01234567890123456789012345678901234567890123456789
    0.8988465674311579538646525953945123668100000000000000+308
   8.9884656743115795386465259539451236681000000000000000+307
   8.9884656743115795386465259539451236681000000000000000+307
   8.9884656743115795386465259539451237E+0307
   1.1079139325602226427183020846172426344000000000000000+276
  no match

I modified gfortran to extend the number of digits converted out to a default 
width of 85 characters and the a and b(1) outputs match to the extent of the 
available digits and yet the comparison still fails and the difference is still 
large.

OK to XFAIL the following for this platform?

default_format_2.f90
default_format_denormal_2.f90
large_real_kind_form_io_2.f90

Regards,

Jerry