message: print diagnostic messages about old compiler version
diff: #pragma message("parsing events from 01.org/perfmon won't be supported because simdjson library is not found in simdjson/singleheader/simdjson.h")
  #pragma message("run 'git clone https://github.com/simdjson/simdjson.git' to get simdjson library")
  #endif
  + #else
  + #pragma message("The compiler is too old, it does not support '__has_include' directive and other c++ features required for simdjson library. Parsing events from 01.org/perfmon won't be supported.")
  #endif
  +#else
  + #pragma message("The compiler is too old (g++ 6 or below). Parsing events from 01.org/perfmon won't be supported.")
  #endif
  