[zorg] [PowerPC] set lld as the default linker on ppc64le-clang-rhel bot

This patch sets lld as the default linker for ppc64le-clang-rhel-test
buildbot.

Reviewed By: gkistanova

Differential Revision: https://reviews.llvm.org/D87993
diff --git a/buildbot/osuosl/master/config/builders.py b/buildbot/osuosl/master/config/builders.py
index 02a8692..9d05ad1 100644
--- a/buildbot/osuosl/master/config/builders.py
+++ b/buildbot/osuosl/master/config/builders.py
@@ -530,7 +530,7 @@
          'factory' : ClangBuilder.getClangCMakeBuildFactory(clean=False,
                                                             checkout_clang_tools_extra=True,
                                                             checkout_compiler_rt=True,
-                                                            checkout_lld=False,
+                                                            checkout_lld=True,
                                                             checkout_libcxx=False,
                                                             useTwoStage=False,
                                                             runTestSuite=True,
@@ -538,6 +538,7 @@
                                                             nt_flags=['--threads=16', '--build-threads=16'],
                                                             extra_cmake_args=["-DLLVM_ENABLE_ASSERTIONS=On", "-DCMAKE_C_COMPILER=clang",
                                                                               "-DCMAKE_CXX_COMPILER=clang++",
+                                                                              "-DCLANG_DEFAULT_LINKER=lld",
                                                                               "-DCMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN:PATH=/opt/rh/devtoolset-7/root/usr",
                                                                               "-DCMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN:PATH=/opt/rh/devtoolset-7/root/usr",
                                                                               "-DLLVM_BINUTILS_INCDIR=/usr/include", "-DBUILD_SHARED_LIBS=ON", "-DLLVM_ENABLE_WERROR=ON",