Fortran : Don't warn for LOGICAL kind conversion PR96319

LOGICAL values will always fit regardless of kind so there
is no need for warnings.

2020-07-29  Mark Eggleston  <markeggleston@gcc.gnu.org>

gcc/fortran/

	PR fortran/96319
	* intrinsic.c (gfc_convert_type_warn):  Add check for
	LOGICAL type so that warnings are not output.

2020-07-29  Mark Eggleston  <markeggleston@gcc.gnu.org>

gcc/testsuite/

	PR fortran/96319
	* gfortran.dg/pr96319.f90: New test.