3rdparty: use a newer wcwidch implementation

src/util/wcwidth.h

@@ -2,15 +2,14 @@
 
 #include <wchar.h>
 
-#ifdef FF_HAVE_WCWIDTH
-static inline int mk_wcwidth(wchar_t ucs) {
-    return wcwidth(ucs);
+#ifndef FF_HAVE_WCWIDTH
+#include "3rdparty/wcwidch/wcwidth.h"
+
+static inline int wcswidth(const wchar_t *pwcs, size_t n)
+{
+    int res = 0;
+    while (n-- > 0)
+        res += wcwidth(*pwcs++);
+    return res;
 }
-static inline int mk_wcswidth(const wchar_t *pwcs, size_t n) {
-    return wcswidth(pwcs, n);
-}
-#else
-// https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
-int mk_wcwidth(wchar_t ucs);
-int mk_wcswidth(const wchar_t *pwcs, size_t n);
 #endif