Store unsigned char value in uint_value instead of int_value

format.h

@@ -1046,7 +1046,7 @@ class MakeValue : public Arg {
   FMT_MAKE_VALUE(double, double_value, DOUBLE)
   FMT_MAKE_VALUE(long double, long_double_value, LONG_DOUBLE)
   FMT_MAKE_VALUE(signed char, int_value, INT)
-  FMT_MAKE_VALUE(unsigned char, int_value, UINT)
+  FMT_MAKE_VALUE(unsigned char, uint_value, UINT)
   FMT_MAKE_VALUE(char, int_value, CHAR)
 
 #if !defined(_MSC_VER) || defined(_NATIVE_WCHAR_T_DEFINED)