[Patch, Fortran] Make -Wall no longer imply -Wcompare-reals

[Thomas Koenig]

Hi Tobias,


> while -Wcompare-reals is a useful option to find bugs, practical
> experience and the discussion here and on c.l.f has shown that this
> option has too many false positives. Hence, it is not suitable for -Wall.

> With patch, -Wall no longer implies -Wcompare-reals.
>
> Build on x86-64-linux.
> OK for the trunk?

Please also revert the change to bessel_5.f90.

I am also currently looking at a way to include the option in -Wextra
(which I think is suitable).  We currently don't handle -Wextra in
gfortran, which makes this a bit more difficult. However, I will
only find time for this in around two weeks.

OK for trunk.

	Thomas