clang-aarch64-full-2stage: build lld for stage2 tests (#139)

A new bitcode format for debug info was added in LLVM in
e419084da7a00b269368aeb95698e0d36b24e8ec (currently reverted).

Several tests started failing for this stage2 builder:
https://lab.llvm.org/buildbot/#/builders/179/builds/9629

The error indicates the tests are using an incompatible lld to load the
new bitcode:
ld.lld: error: Invalid value (Producer: 'LLVM19.0.0git' Reader: 'LLVM
17.0.6')

Locally, re-enabling the currently reverted patch, these tests pass if
LLD is built with LLVM_ENABLE_PROJECTS, and fail otherwise.

Author: OCHyams

buildbot/osuosl/master/config/builders.py

@@ -425,7 +425,7 @@
     'factory' : ClangBuilder.getClangCMakeBuildFactory(
                     clean=False,
                     checkout_flang=True,
-                    checkout_lld=False,
+                    checkout_lld=True,
                     useTwoStage=True,
                     testStage1=False,
                     runTestSuite=True,