static-destruct: Reduce transitive includes

src/basic/static-destruct.h

@@ -2,10 +2,11 @@
 
 #pragma once
 
-#include "alloc-util.h"
 #include "macro.h"
 #include "memory-util.h"
 
+typedef void (*free_func_t)(void *p);
+
 /* A framework for registering static variables that shall be freed on shutdown of a process. It's a bit like gcc's
  * destructor attribute, but allows us to precisely schedule when we want to free the variables. This is supposed to
  * feel a bit like the gcc cleanup attribute, but for static variables. Note that this does not work for static