Fixes error
Rework block processing benchmark code

* Replace -benchmark (and the related fBenchmark) with a regular debug option, -debug=bench.
* Increase coverage and granularity of individual block processing steps.
* Add cummulative times.
Added systemd .service file in order to help distributions integrate bitcoind.
Merge pull request #4577

0c3e101 Added systemd .service file in order to help distributions integrate bitcoind. (Aitor Pazos)
Merge pull request #4593

d70bc52 Rework block processing benchmark code (Pieter Wuille)
Merge pull request #4104

68aa01e Fixes error (Ian Carroll)