decl.c (variable_decl): Don't share charlen structs if length == NULL.

decl.c (variable_decl): Don't share charlen structs if length == NULL.

	* decl.c (variable_decl): Don't share charlen structs if
	length == NULL.
	* trans-decl.c (create_function_arglist): Assert
	f->sym->ts.cl->backend_decl is NULL instead of unsharing
	charlen struct here.

	* gfortran.dg/assumed_charlen_sharing.f90: New test.

From-SVN: r127748