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

fusl/src/ctype/wcwidth.c

+#include <wchar.h>
+
+static const unsigned char table[] = {
+#include "nonspacing.h"
+};
+
+static const unsigned char wtable[] = {
+#include "wide.h"
+};
+
+int wcwidth(wchar_t wc)
+{
+        if (wc < 0xffU)
+                return (wc+1 & 0x7f) >= 0x21 ? 1 : wc ? -1 : 0;
+        if ((wc & 0xfffeffffU) < 0xfffe) {
+                if ((table[table[wc>>8]*32+((wc&255)>>3)]>>(wc&7))&1)
+                        return 0;
+                if ((wtable[wtable[wc>>8]*32+((wc&255)>>3)]>>(wc&7))&1)
+                        return 2;
+                return 1;
+        }
+        if ((wc & 0xfffe) == 0xfffe)
+                return -1;
+        if (wc-0x20000U < 0x20000)
+                return 2;
+        if (wc == 0xe0001 || wc-0xe0020U < 0x5f || wc-0xe0100 < 0xef)
+                return 0;
+        return 1;
+}