QT MSVC2017 ratio chrono

如果引用了stdint.h可能会引发一些列错误，各种未申明和语法错误。

参加以下帖子解决问题

https://github.com/ftylitak/qzxing/issues/54

 

When compiling QZXing with Qt 5.9.2 and MSVC2017 64bit(Visual C++ Compiler 15.0) a bunch of errors are occuring in "ratio" and "chrono". One of them is:

"C2065: "INTMAX_MAX": undeclared identifier

QZXing ships with a version of stdint.h. In this, the define segment
#if !defined(__cplusplus) || defined(__STDC_LIMIT_MACROS)
starting at line 131 is grey. Therefore INTMAX_MAX is truely undefined.

By manually adding
#define __STDC_LIMIT_MACROS
in before of line 131, i could manage to get all ratio and chrono errors removed.