maxlog is broken, log ids are always unique, thus breaking maxlog

[oxinabox]

The following comes from julia 0.7 (release) or 1.0

julia> for ii in 1:10
       @info("this", maxlog=5)
       end
[ Info: this
[ Info: this
[ Info: this
[ Info: this
[ Info: this
[ Info: this
[ Info: this
[ Info: this
[ Info: this
[ Info: this

Notice that it was printed more than 5 times.

I recall that this used to work, to print it only 5 times.
So I checked on an old fork I had kicking around,
with some unrelated changes.

  | | |_| | | | (_| |  |  Version 0.7.0-beta.197 (2018-07-10 09:42 UTC)
 _/ |\__'_|_|_|\__'_|  |  patch-10/a4ca72175a* (fork: 8 commits, 72 days)
|__/                   |  x86_64-linux-gnu

julia> for ii in 1:10
       @info("this", maxlog=5)
       end
[ Info: this
[ Info: this
[ Info: this
[ Info: this
[ Info: this

---

I started looking for this, because
the automatic overwriting of the last log message in
https://github.com/oxinabox/OhMyLog.jl
used to work in for loops.
And it also depends on the id being the same inside a loop.

And I added a print statement, and it confirmed that each time the @info triggered,
the id was incremented by 1

[KristofferC]

Dup of #28786