analyzer: fix ICE on unknown index in CONSTRUCTOR [PR96860]

analyzer: fix ICE on unknown index in CONSTRUCTOR [PR96860]

PR analyzer/96860 reports an ICE inside CONSTRUCTOR-handling with
--param analyzer-max-svalue-depth=0 when attempting to build a
binding_map for the CONSTRUCTOR's values.

The issue is that when handling (index, value) pairs for initializing
an array, the index values for the elements exceeds the svalue
complexity limit, and the index is thus treated as unknown, leading to
a symbolic rather than concrete offset for each array element.

This patch updates the CONSTRUCTOR-handling code so that it can
fail, returning an unknown value for the overall value of the
constructor for this case, fixing the ICE.

gcc/analyzer/ChangeLog:
	PR analyzer/96860
	* region.cc (decl_region::get_svalue_for_constructor): Support
	apply_ctor_to_region failing.
	* store.cc (binding_map::apply_ctor_to_region): Add failure
	handling.
	(binding_map::apply_ctor_val_to_range): Likewise.
	(binding_map::apply_ctor_pair_to_child_region): Likewise.  Replace
	assertion that child_base_offset is not symbolic with error
	handling.
	* store.h (binding_map::apply_ctor_to_region): Convert return type
	from void to bool.
	(binding_map::apply_ctor_val_to_range): Likewise.
	(binding_map::apply_ctor_pair_to_child_region): Likewise.

gcc/testsuite/ChangeLog:
	PR analyzer/96860
	* gcc.dg/analyzer/pr96860-1.c: New test.
	* gcc.dg/analyzer/pr96860-2.c: New test.