I moved the library implementation of IEEE_VALUE in libgfortran from
Fortran to C code, which gives us access to GCC's built-ins for NaN generation
(both quiet and signalling). It will be perform better than the current
Fortran implementation.

libgfortran/ChangeLog:

	PR fortran/82207
	* mk-kinds-h.sh: Add values for TINY.
	* ieee/ieee_arithmetic.F90: Call C helper functions for
	IEEE_VALUE.
	* ieee/ieee_helper.c: New functions ieee_value_helper_N for each
	floating-point type.

gcc/testsuite/ChangeLog:

	PR fortran/82207
	* gfortran.dg/ieee/ieee_10.f90: Do not create signaling NaNs.
	* gfortran.dg/ieee/signaling_2.f90: New test.
	* gfortran.dg/ieee/signaling_2_c.c: New file.