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

fusl/src/dirent/fdopendir.c

Index: fusl/src/dirent/fdopendir.c
diff --git a/fusl/src/dirent/fdopendir.c b/fusl/src/dirent/fdopendir.c
new file mode 100644
index 0000000000000000000000000000000000000000..c377271da53919acb39f5929ded9d77f874f7e55
--- /dev/null
+++ b/fusl/src/dirent/fdopendir.c
@@ -0,0 +1,27 @@
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdlib.h>
+#include "__dirent.h"
+
+DIR *fdopendir(int fd)
+{
+	DIR *dir;
+	struct stat st;
+
+	if (fstat(fd, &st) < 0) {
+		return 0;
+	}
+	if (!S_ISDIR(st.st_mode)) {
+		errno = ENOTDIR;
+		return 0;
+	}
+	if (!(dir = calloc(1, sizeof *dir))) {
+		return 0;
+	}
+
+	fcntl(fd, F_SETFD, FD_CLOEXEC);
+	dir->fd = fd;
+	return dir;
+}