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

fusl/src/misc/ptsname.c

Index: fusl/src/misc/ptsname.c
diff --git a/fusl/src/misc/ptsname.c b/fusl/src/misc/ptsname.c
new file mode 100644
index 0000000000000000000000000000000000000000..a34779276fa011be935e1db0860d775165ba8729
--- /dev/null
+++ b/fusl/src/misc/ptsname.c
@@ -0,0 +1,15 @@
+#include <stdlib.h>
+#include <errno.h>
+
+int __ptsname_r(int, char *, size_t);
+
+char *ptsname(int fd)
+{
+	static char buf[9 + sizeof(int)*3 + 1];
+	int err = __ptsname_r(fd, buf, sizeof buf);
+	if (err) {
+		errno = err;
+		return 0;
+	}
+	return buf;
+}