Add rule to build tar.gz file.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1592 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/Makefile b/docs/Makefile
index 12645d8..da24e8e 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -1,2 +1,6 @@
 doxygen-files:
 	/home/vadve/lattner/bin/doxygen doxygen.cfg
+
+doxygen.tar.gz: doxygen/index.html
+	rm -rf $@
+	gtar czvf $@ doxygen