format: we need to include the last byte

We skip the last byte, which I guess happens to work for us, but is still improper.

Also use int because unsigned char is bad for ARM64 and cannot exceed the value of an unsigned char anyway.

Author: SiliconA-Z

stl/src/format.cpp

@@ -31,7 +31,7 @@ extern "C" [[nodiscard]] __std_win_error __stdcall __std_get_cvt(
             break;
         }
 
-        for (unsigned char _First = _Info.LeadByte[_Idx], _Last = _Info.LeadByte[_Idx + 1]; _First != _Last; ++_First) {
+        for (int _First = _Info.LeadByte[_Idx], _Last = _Info.LeadByte[_Idx + 1]; _First <= _Last; ++_First) {
             _Pcvt->_Isleadbyte[_First >> 3] |= 1u << (_First & 0b111u);
         }
     }