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

fusl/src/stdio/fputws.c

+#include "stdio_impl.h"
+#include "locale_impl.h"
+#include <wchar.h>
+
+int fputws(const wchar_t *restrict ws, FILE *restrict f)
+{
+        unsigned char buf[BUFSIZ];
+        size_t l=0;
+        locale_t *ploc = &CURRENT_LOCALE, loc = *ploc;
+
+        FLOCK(f);
+
+        fwide(f, 1);
+        *ploc = f->locale;
+
+        while (ws && (l = wcsrtombs((void *)buf, (void*)&ws, sizeof buf, 0))+1 > 1)
+                if (__fwritex(buf, l, f) < l) {
+                        FUNLOCK(f);
+                        *ploc = loc;
+                        return -1;
+                }
+
+        FUNLOCK(f);
+
+        *ploc = loc;
+        return l; /* 0 or -1 */
+}
+
+weak_alias(fputws, fputws_unlocked);