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

fusl/src/malloc/lite_malloc.c

+#include <stdlib.h>
+#include <stdint.h>
+#include <limits.h>
+#include <errno.h>
+#include "libc.h"
+
+#define ALIGN 16
+
+void *__expand_heap(size_t *);
+
+static void *__simple_malloc(size_t n)
+{
+        static char *cur, *end;
+        static volatile int lock[2];
+        size_t align=1, pad;
+        void *p;
+
+        if (!n) n++;
+        while (align<n && align<ALIGN)
+                align += align;
+
+        LOCK(lock);
+
+        pad = -(uintptr_t)cur & align-1;
+
+        if (n <= SIZE_MAX/2 + ALIGN) n += pad;
+
+        if (n > end-cur) {
+                size_t m = n;
+                char *new = __expand_heap(&m);
+                if (!new) {
+                        UNLOCK(lock);
+                        return 0;
+                }
+                if (new != end) {
+                        cur = new;
+                        n -= pad;
+                        pad = 0;
+                }
+                end = new + m;
+        }
+
+        p = cur + pad;
+        cur += n;
+        UNLOCK(lock);
+        return p;
+}
+
+weak_alias(__simple_malloc, malloc);
+weak_alias(__simple_malloc, __malloc0);