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

fusl/src/temp/mkdtemp.c

+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/stat.h>
+
+char *__randname(char *);
+
+char *mkdtemp(char *template)
+{
+        size_t l = strlen(template);
+        int retries = 100;
+
+        if (l<6 || memcmp(template+l-6, "XXXXXX", 6)) {
+                errno = EINVAL;
+                return 0;
+        }
+
+        do {
+                __randname(template+l-6);
+                if (!mkdir(template, 0700)) return template;
+        } while (--retries && errno == EEXIST);
+
+        memcpy(template+l-6, "XXXXXX", 6);
+        return 0;
+}