gcc's std:regex implementation seems to be buggy when char is signed as on x86. Avoid regex ranges that are of different sign.

[aholzinger]

Hi Sergio,

I found an issue on Ubuntu 22.04 with gcc 11 on x86-64. It seems as the std::regex implementation has issues if ranges over the sign border (0x7F to 0x80) are used like in numeric value from 0x0E to 0xFF.

Neither on Windows/Visual Studio nor on Raspi OS 64 bit the issue is happening. On Windows obsiously the std::regex implementation is different, on ARM64 the char is unsigned (while on x86-64 it's signed).

The proposed fix obviously is a work-around, but it will be necessary for Linux x86-64 I think.