[PATCH v2][PR libgfortran/78314] Fix ieee_support_halting

[FX]

> gcc/testsuite/
> 2016-11-16  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	PR libgfortran/78314
> 	* gfortran.dg/ieee/ieee_6.f90: Use ieee_support_halting.
> 
> libgfortran/
> 2016-11-16  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	PR libgfortran/78314
> 	* config/fpu-glibc.h (support_fpu_trap): Use feenableexcept.

OK to commit.

FX