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

fusl/src/ctype/iswspace.c

+#include <wchar.h>
+#include <wctype.h>
+#include "libc.h"
+
+/* Our definition of whitespace is the Unicode White_Space property,
+ * minus non-breaking spaces (U+00A0, U+2007, and U+202F) and script-
+ * specific characters with non-blank glyphs (U+1680 and U+180E). */
+
+int iswspace(wint_t wc)
+{
+        static const wchar_t spaces[] = {
+                ' ', '\t', '\n', '\r', 11, 12,  0x0085,
+                0x2000, 0x2001, 0x2002, 0x2003, 0x2004, 0x2005,
+                0x2006, 0x2008, 0x2009, 0x200a,
+                0x2028, 0x2029, 0x205f, 0x3000, 0
+        };
+        return wc && wcschr(spaces, wc);
+}
+
+int __iswspace_l(wint_t c, locale_t l)
+{
+        return iswspace(c);
+}
+
+weak_alias(__iswspace_l, iswspace_l);