Add support for comma-separated include/exclude filters to runtime benchmarks

[Kobzol]

Before the CLI help claimed commas are supported, but they weren't.

[nnethercote]

It would be nice if the compile-time and runtime benchmarks used the same code for this. E.g. the compile time benchmarks have some checking so that if you specify an entry that doesn't match anything you get an error, which is useful for catching typos.

[Kobzol]

I have it in my TODO list, it's a bit more complicated because the benchmark names are distributed amongst several binaries. Maybe I'll move the filtering to collector from benchlib.