analyzer: remove redundant return value from various impl_call_*

analyzer: remove redundant return value from various impl_call_*

gcc/analyzer/ChangeLog:
	* region-model-impl-calls.cc (region_model::impl_call_alloca):
	Drop redundant return value.
	(region_model::impl_call_builtin_expect): Likewise.
	(region_model::impl_call_calloc): Likewise.
	(region_model::impl_call_malloc): Likewise.
	(region_model::impl_call_memset): Likewise.
	(region_model::impl_call_operator_new): Likewise.
	(region_model::impl_call_operator_delete): Likewise.
	(region_model::impl_call_strlen): Likewise.
	* region-model.cc (region_model::on_call_pre): Fix return value of
	known functions that don't have unknown side-effects.
	* region-model.h (region_model::impl_call_alloca): Drop redundant
	return value.
	(region_model::impl_call_builtin_expect): Likewise.
	(region_model::impl_call_calloc): Likewise.
	(region_model::impl_call_malloc): Likewise.
	(region_model::impl_call_memset): Likewise.
	(region_model::impl_call_strlen): Likewise.
	(region_model::impl_call_operator_new): Likewise.
	(region_model::impl_call_operator_delete): Likewise.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>