Reproducible builds

[laeti-tia]

Compiling the source code from this repository we get a lot of warnings like:

../I2util/errlog.h:105:33: warning: macro "__DATE__" might prevent reproducible builds [-Wdate-time]
 #define I2ErrLog I2ErrLocation_(__FILE__, __DATE__, __LINE__); \

We could either just remove the usage of the __DATE__ macro or, better, replace it with the i2util version number. See the function definition.