Fortran: Fix for class defined operators [PR99125].

Fortran: Fix for class defined operators [PR99125].

2021-03-13  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
	PR fortran/99125
	* trans-array.c (gfc_conv_expr_descriptor): For deferred length
	length components use the ss_info string length instead of
	gfc_get_expr_charlen. Make sure that the deferred string length
	is a variable before assigning to it. Otherwise use the expr.
	* trans-expr.c (gfc_conv_string_length): Make sure that the
	deferred string length is a variable before assigning to it.

gcc/testsuite/
	PR fortran/99125
	* gfortran.dg/alloc_deferred_comp_1.f90: New test.