Have wcwidth() return 0 for marks instead of -1

Since kitty always treats marks as combinig chars, this allows us to
remove a few unnecessary branches

kitty/emoji.h

@@ -1,4 +1,4 @@
-// unicode data, built from the unicode standard on: 2018-02-04
+// unicode data, built from the unicode standard on: 2018-02-05
 // see gen-wcwidth.py
 #pragma once
 #include "data-types.h"

kitty/screen.c

@@ -278,7 +278,7 @@ unsigned int
 safe_wcwidth(uint32_t ch) {
     int ans = wcwidth_std(ch);
     if (ans < 0) ans = 1;
-    return MIN(2, ans);
+    return ans;
 }
 
 static inline void
@@ -1445,8 +1445,7 @@ screen_wcswidth(Screen UNUSED *self, PyObject *str) {
     unsigned long ans = 0;
     for (i = 0; i < len; i++) {
         char_type ch = PyUnicode_READ(kind, data, i);
-        bool is_cc = is_combining_char(ch);
-        ans += is_cc ? 0 : safe_wcwidth(ch);
+        ans += safe_wcwidth(ch);
     }
     return PyLong_FromUnsignedLong(ans);
 }

kitty/unicode-data.c

@@ -1,4 +1,4 @@
-// unicode data, built from the unicode standard on: 2018-02-04
+// unicode data, built from the unicode standard on: 2018-02-05
 // see gen-wcwidth.py
 #include "data-types.h"