This patch adds the necessary builders to zorg to get the -fno-exceptions libcxx library variant building. I've only used those build-slaves which I have got explicit permission to use for this purpose.
As discussed on the cfe-dev list, these builders won't run the libcxx test suite (they will, in the near future, when we adapt the tests).
These builders will ensure that we don't break the -fno-exceptions library build. This patch can only go in once D14292 is sorted.