Simple Logger in C++
Some things to note;

When doing time related things in C++, use std::chrono, not clock().
Your log will not work if it's used in multiple files. Instead of being in a .h file, put the definition of the logger in a cpp file and build both together.
Use include guards for header files

    #ifndef LOG_H
    #define LOG_H

    // Code

    #endif


Define constructors and use them properly and get rid of configure.

    Log(std::string fileName, bool printToConsole, bool saveToFile) :
        logFileName(fileName),
        print(printToConsole),
        save(saveToFile)
    {
    }


Do not use underscores for naming things. General rules for c++ are class names are PascalCase and functions are camelCase.
std::cout is slow, consider using sprintf to make it faster.
Don't write to a file every time you call log. Opening files and writing to them is slow. Consider writing to the file on a timestamp or aggregating a few logs before writing them.