[fortran,patch] Extend IEEE support to all real kinds

[FX]

> Can you please also introduce tests for ieee exceptions for long
> double and __float128 types (as is done for real and double in
> gfortran.dg/ieee/ieee_1.F90) as well as test for supported rounding
> modes as done for real and double in gfortran.dg/ieee/rounding_1.f90 ?
> 
> On x86_64, these new tests will exercise exceptions and rounding modes
> for __float128 soft-fp library, in addition to x87 long double tests.

I’ve now introduced the tests for rounding (large_2.f90) and exceptions (large_3.F90):

Adding         gfortran.dg/ieee/large_2.f90
Adding         gfortran.dg/ieee/large_3.F90
Transmitting file data ...
Committed revision 226670.