message: core: use strftime instead of put_time
  We can't use put_time because it is not supported by GCC versions < 5.0.
diff: #include <android/log.h>
  #else
  #include <iostream>
  -#include <iomanip>
  #include <ctime>
  #endif
  @@ -84,10 +83,15 @@ public:
  #else
  // Time output taken from:
  - // https://stackoverflow.com/questions/16357999#answer-16358111
  - auto t = std::time(nullptr);
  - auto tm = *std::localtime(&t);
  - std::cout << "[" << std::put_time(&tm, "%H:%M:%S");
  + // https://stackoverflow.com/questions/16357999#answer-16358264
  +
  +
  + time_t rawtime;
  + time(&rawtime);
  + struct tm *timeinfo = localtime(&rawtime);
  + char time_buffer[10] {}; // We need 8 characters + \0
  + strftime(time_buffer, sizeof(time_buffer), "%I:%M:%S", timeinfo);
  + std::cout << "[" << time_buffer;
  switch (_log_level) {
  case LogLevel::Debug:
  