Fortran: reject module variable as character length in PARAMETER [PR104349]

gcc/fortran/ChangeLog:

	PR fortran/104349
	* expr.cc (check_restricted): Adjust check for valid variables in
	restricted expressions: make no exception for module variables.

gcc/testsuite/ChangeLog:

	PR fortran/104349
	* gfortran.dg/der_charlen_1.f90: Adjust dg-patterns.
	* gfortran.dg/pr104349.f90: New test.