xo-gc stack: coverage improvement + related tidying

utest/IAllocator_Any.test.cpp

@@ -0,0 +1,29 @@
+/** @file IAllocator_Any.test.cpp
+ *
+ *  @author Roland Conybeare, May 2026
+ **/
+
+#include <xo/alloc2/Allocator.hpp>
+#include <catch2/catch.hpp>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <signal.h>
+
+namespace xo {
+    using xo::mm::AAllocator;
+
+    namespace ut {
+
+        TEST_CASE("IAllocator_Any", "[alloc2][death]")
+        {
+            // null allocator
+            obj<AAllocator> alloc_any;
+
+            // NOTE: tried using a fork() strategy to verify termination,
+            //       but child process doesn't get measured by gcov
+        }
+
+    } /*namespace ut*/
+} /*namespace xo*/
+
+/* end IAllocator_Any.test.cpp */