Update clang dependency to 3.9

Reviewers: buda, teon.banek

Reviewed By: teon.banek

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1479

init

@@ -4,7 +4,7 @@
 # allows source modification and static compilation. Unfortunately, it is quite
 # a pain to set up the boost build process.
 required_pkgs=(git arcanist # source code control
-               cmake clang-3.8 llvm-3.8 pkg-config # build system
+               cmake clang-3.9 llvm-3.9 pkg-config # build system
                curl wget # for downloading libs
                uuid-dev default-jre-headless # required by antlr
                libreadline-dev # for memgraph console