message: more instructions for simdjson
diff: #define PCM_SIMDJSON_AVAILABLE
  #else
  #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
  #endif
  #endif
  