Third attempt to fix Sphinx bot

Bot now complaining about -flto=thin reference, used similar workaround
for that failure.

llvm-svn: 282154
diff --git a/clang/docs/CommandGuide/clang.rst b/clang/docs/CommandGuide/clang.rst
index cee9b18..7a61666 100644
--- a/clang/docs/CommandGuide/clang.rst
+++ b/clang/docs/CommandGuide/clang.rst
@@ -338,7 +338,7 @@
   The default for :option:`-flto` is "full", in which the
   LLVM bitcode is suitable for monolithic Link Time Optimization (LTO), where
   the linker merges all such modules into a single combined module for
-  optimization. With :option:`-flto=thin`, :doc:`ThinLTO <../ThinLTO>`
+  optimization. With "thin", :doc:`ThinLTO <../ThinLTO>`
   compilation is invoked instead.
 
 Driver Options