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

fusl/src/stdio/tmpfile.c

Index: fusl/src/stdio/tmpfile.c
diff --git a/fusl/src/stdio/tmpfile.c b/fusl/src/stdio/tmpfile.c
new file mode 100644
index 0000000000000000000000000000000000000000..525090aa066d49cc20a4a762b17a4d54a3ec1b4f
--- /dev/null
+++ b/fusl/src/stdio/tmpfile.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include "stdio_impl.h"
+
+#define MAXTRIES 100
+
+char *__randname(char *);
+
+FILE *tmpfile(void)
+{
+	char s[] = "/tmp/tmpfile_XXXXXX";
+	int fd;
+	FILE *f;
+	int try;
+	for (try=0; try<MAXTRIES; try++) {
+		__randname(s+13);
+		fd = sys_open(s, O_RDWR|O_CREAT|O_EXCL, 0600);
+		if (fd >= 0) {
+#ifdef SYS_unlink
+			__syscall(SYS_unlink, s);
+#else
+			__syscall(SYS_unlinkat, AT_FDCWD, s, 0);
+#endif
+			f = __fdopen(fd, "w+");
+			if (!f) __syscall(SYS_close, fd);
+			return f;
+		}
+	}
+	return 0;
+}
+
+LFS64(tmpfile);