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

fusl/src/ctype/wctrans.c

+#include <wctype.h>
+#include <string.h>
+#include "libc.h"
+
+wctrans_t wctrans(const char *class)
+{
+        if (!strcmp(class, "toupper")) return (wctrans_t)1;
+        if (!strcmp(class, "tolower")) return (wctrans_t)2;
+        return 0;
+}
+
+wint_t towctrans(wint_t wc, wctrans_t trans)
+{
+        if (trans == (wctrans_t)1) return towupper(wc);
+        if (trans == (wctrans_t)2) return towlower(wc);
+        return wc;
+}
+
+wctrans_t __wctrans_l(const char *s, locale_t l)
+{
+        return wctrans(s);
+}
+
+wint_t __towctrans_l(wint_t c, wctrans_t t, locale_t l)
+{
+        return towctrans(c, t);
+}
+
+weak_alias(__wctrans_l, wctrans_l);
+weak_alias(__towctrans_l, towctrans_l);