Guard madvise ENOMEM and stabilize pool/tiny front v3

core/hakmem_tiny_init.inc

@@ -9,6 +9,11 @@
 //
 // Cold path only - called once at startup.
 
+// Some build configurations expect this hook but do not provide an implementation.
+// Provide a no-op stub so that non-debug builds continue to link without optional
+// signal-dump support.
+static inline void hak_tiny_enable_signal_dump(void) { }
+
 void hak_tiny_init(void) {
     if (g_tiny_initialized) return;