Fix function-type mismatch in dynamic_loading test

main.cpp loads and calls method_get_ids/overrider_get_ids through
policy_ids_fn = const void**(), but the exported functions returned
const void*. The pointer reinterpretation is harmless at the ABI level,
so the test passes everywhere except the clang UBSan job, where
-fsanitize=function traps the call through the mismatched function-pointer
type and aborts. Declare the exports to return const void** to match.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: jll63

test/dynamic_loading/method.cpp

@@ -40,7 +40,7 @@ BOOST_OPENMETHOD_OVERRIDE(
 
 extern "C" {
 
-BOOST_SYMBOL_EXPORT const void* method_get_ids() {
+BOOST_SYMBOL_EXPORT const void** method_get_ids() {
     return get_ids();
 }
 

test/dynamic_loading/overrider.cpp

@@ -31,7 +31,7 @@ BOOST_OPENMETHOD_CLASSES(Animal, Dog);
 
 extern "C" {
 
-BOOST_SYMBOL_EXPORT const void* overrider_get_ids() {
+BOOST_SYMBOL_EXPORT const void** overrider_get_ids() {
     return get_ids();
 }