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

fusl/src/multibyte/mbsinit.c

Index: fusl/src/multibyte/mbsinit.c
diff --git a/fusl/src/multibyte/mbsinit.c b/fusl/src/multibyte/mbsinit.c
new file mode 100644
index 0000000000000000000000000000000000000000..e001d84443664406ad9d3a98ea59afe9316ee552
--- /dev/null
+++ b/fusl/src/multibyte/mbsinit.c
@@ -0,0 +1,12 @@
+/* 
+ * This code was written by Rich Felker in 2010; no copyright is claimed.
+ * This code is in the public domain. Attribution is appreciated but
+ * unnecessary.
+ */
+
+#include <wchar.h>
+
+int mbsinit(const mbstate_t *st)
+{
+	return !st || !*(unsigned *)st;
+}