utf8: export utf8_char_console_width()

src/basic/utf8.h

@@ -59,4 +59,5 @@ static inline char32_t utf16_surrogate_pair_to_unichar(char16_t lead, char16_t t
 }
 
 size_t utf8_n_codepoints(const char *str);
+int utf8_char_console_width(const char *str);
 size_t utf8_console_width(const char *str);