[Docs][JIT] Update the clang++ invocation lines in the kaleidoscope docs.

The old examples had missing/incorrect flags that were causing failures on newer
versions of clang and the tutorial code.

llvm-svn: 221419
diff --git a/llvm/docs/tutorial/LangImpl7.rst b/llvm/docs/tutorial/LangImpl7.rst
index 849ce50..c4c7233 100644
--- a/llvm/docs/tutorial/LangImpl7.rst
+++ b/llvm/docs/tutorial/LangImpl7.rst
@@ -847,7 +847,7 @@
 .. code-block:: bash
 
     # Compile
-    clang++ -g toy.cpp `llvm-config --cppflags --ldflags --libs core jit native` -O3 -o toy
+    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core jit native` -O3 -o toy
     # Run
     ./toy