Add a "fork" of musl as //fusl.

fusl/src/search/insque.c

+#include <search.h>
+
+struct node {
+        struct node *next;
+        struct node *prev;
+};
+
+void insque(void *element, void *pred)
+{
+        struct node *e = element;
+        struct node *p = pred;
+
+        if (!p) {
+                e->next = e->prev = 0;
+                return;
+        }
+        e->next = p->next;
+        e->prev = p;
+        p->next = e;
+        if (e->next)
+                e->next->prev = e;
+}
+
+void remque(void *element)
+{
+        struct node *e = element;
+
+        if (e->next)
+                e->next->prev = e->prev;
+        if (e->prev)
+                e->prev->next = e->next;
+}