Update the llvm repo to use the debian jessie url

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>
(cherry picked from commit 73672c5bd8ad170224957734bd1eaf20b11680ba)

Dockerfile

@@ -33,7 +33,7 @@ RUN echo deb http://ppa.launchpad.net/zfs-native/stable/ubuntu trusty main > /et
 # add llvm repo
 RUN apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 6084F3CF814B57C1CF12EFD515CF4D18AF4F7421 \
 	|| apt-key adv --keyserver hkp://pgp.mit.edu:80 --recv-keys 6084F3CF814B57C1CF12EFD515CF4D18AF4F7421
-RUN echo deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty main > /etc/apt/sources.list.d/llvm.list
+RUN echo deb http://llvm.org/apt/jessie/ llvm-toolchain-jessie-3.8 main > /etc/apt/sources.list.d/llvm.list
 
 # allow replacing httpredir mirror
 ARG APT_MIRROR=httpredir.debian.org