A bit different handling for the lto param.

git-svn-id: https://llvm.org/svn/llvm-project/zorg/trunk@284767 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/zorg/buildbot/builders/ClangLTOBuilder.py b/zorg/buildbot/builders/ClangLTOBuilder.py
index e0ff2d3..b55c3a8 100644
--- a/zorg/buildbot/builders/ClangLTOBuilder.py
+++ b/zorg/buildbot/builders/ClangLTOBuilder.py
@@ -244,6 +244,9 @@
         # By default we link with LLD.
         depends_on_projects = ['llvm', 'clang', 'lld']
 
+    if lto is None:
+        lto = 'ON'
+
     if jobs is None:
         jobs = "%(jobs)s"
 
@@ -315,7 +318,7 @@
     # Build all the remaining stages with exactly the same configuration.
 
     CmakeCommand.applyRequiredOptions(extra_configure_args, [
-        ('-DLLVM_ENABLE_LTO=', lto.upper() or 'ON'),
+        ('-DLLVM_ENABLE_LTO=', lto),
         ])
 
     # If we build LLD, we would link with LLD.