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

fusl/src/stdio/fwide.c

Index: fusl/src/stdio/fwide.c
diff --git a/fusl/src/stdio/fwide.c b/fusl/src/stdio/fwide.c
new file mode 100644
index 0000000000000000000000000000000000000000..8410b1530780d894e5afc2c9e9769011e75b0ac2
--- /dev/null
+++ b/fusl/src/stdio/fwide.c
@@ -0,0 +1,15 @@
+#include "stdio_impl.h"
+#include "locale_impl.h"
+
+int fwide(FILE *f, int mode)
+{
+	FLOCK(f);
+	if (mode) {
+		if (!f->locale) f->locale = MB_CUR_MAX==1
+			? C_LOCALE : UTF8_LOCALE;
+		if (!f->mode) f->mode = mode>0 ? 1 : -1;
+	}
+	mode = f->mode;
+	FUNLOCK(f);
+	return mode;
+}