Builds and webrevs

[Aleksey Shipilev]

Hi,

When ZGC was upstreamed, I disabled the builders thinking most of the development would happen
upstream. But, seeing how some features are incubating in zgc/zgc, I have re-enabled the builders
for it:
  https://builds.shipilev.net/openjdk-zgc/

Additionally, there are automatically generated webrevs against jdk/jdk:
  https://builds.shipilev.net/patch-openjdk-zgc/latest/

Cheers,
-Aleksey