[AArch64][LLDB] Remove lit workers limit

[DavidSpickett]

Summary

This bot will soon be running on a new machine where this
thread limit is not needed anymore, as the new host is not shared.

While we're here, use lld as the linker.

[DavidSpickett]

There is a silent bot already running on the new machine https://lab.llvm.org/staging/#/builders/73. So far we are matching the speed of the existing bot, even with this restriction in place. This change should take around 4 minutes off of the testing step.

[DavidSpickett]

https://github.com/llvm/llvm-zorg/commit/c410827ef27e89c8103ab6054b108f7d25c0d817

buildbot/osuosl/master/config/builders.py

# LLDB builders.
     'tags'  : ["lldb"],
     'workernames' : ["linaro-lldb-aarch64-ubuntu"],
     'builddir': "lldb-aarch64-ubuntu",
     'factory' : LLDBBuilder.getLLDBCMakeBuildFactory(
                     test=True,
                     clean=True,
                     extra_cmake_args=[
                         '-DLLVM_ENABLE_ASSERTIONS=True',
-                        '-DLLVM_LIT_ARGS=-vj 4',
-                        '-DLLVM_USE_LINKER=gold'])},
+                        '-DLLVM_LIT_ARGS=-v',
+                        '-DLLVM_USE_LINKER=lld'])},
 
     {'name' : "lldb-arm-ubuntu",
     'tags'  : ["lldb"],
     'workernames' : ["linaro-lldb-arm-ubuntu"],
     'builddir': "lldb-arm-ubuntu",
     'factory' : LLDBBuilder.getLLDBCMakeBuildFactory(
                     test=True,
                     clean=True,