Add llvm-symbolizer from system package in llvm-premerge-linux-runners

[mizvekov]

It would be useful if ours bots already had the system llvm-symbolizer set up in PATH from the get go.

Having to setup and use the just-built one is a bit wasteful, as we don't need a debug version of it, we want it to go fast.

[llvmbot]

@llvm/issue-subscribers-infrastructure

Author: Matheus Izvekov (mizvekov)

It would be useful if ours bots already had the system llvm-symbolizer set up in PATH from the get go.

Having to setup and using the just-built one is a bit wasteful, as we don't need a debug version of it, we want it to go fast.

[boomanaiden154]

This was fixed in 339f58d.