fortran: Compare non-constant bound expressions. [PR105379]

fortran: Compare non-constant bound expressions. [PR105379]

Starting with r12-8235-gfa5cd7102da676dcb1757b1288421f5f3439ae0e,
class descriptor types are compared to detect duplicate declarations.

This caused ICEs as the comparison of array spec supported only constant
explicit bounds, but dummy class variable descriptor types can have a
_data field with non-constant array spec bounds.

This change adds support for non-constant bounds.  For that,
gfc_dep_compare_expr is used.  It does probably more than strictly
necessary, but using it avoids rewriting a specific comparison function,
making mistakes and forgetting cases.

	PR fortran/103662
	PR fortran/105379

gcc/fortran/ChangeLog:

	* array.cc (compare_bounds): Use bool as return type.
	Support non-constant expressions.
	(gfc_compare_array_spec): Update call to compare_bounds.

gcc/testsuite/ChangeLog:

	* gfortran.dg/class_dummy_8.f90: New test.
	* gfortran.dg/class_dummy_9.f90: New test.