Migrate the i586::avx module to vendor types (rust-lang#286)

Closes rust-lang#285

Author: alexcrichton

ci/docker/i586-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:17.04
+FROM ubuntu:17.10
 RUN apt-get update && apt-get install -y --no-install-recommends \
   gcc-multilib \
   libc6-dev \

ci/docker/i686-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:17.04
+FROM ubuntu:17.10
 RUN apt-get update && apt-get install -y --no-install-recommends \
   gcc-multilib \
   libc6-dev \

ci/docker/x86_64-unknown-linux-gnu-emulated/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:17.04
+FROM ubuntu:17.10
 RUN apt-get update && apt-get install -y --no-install-recommends \
   gcc \
   libc6-dev \

ci/docker/x86_64-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:17.04
+FROM ubuntu:17.10
 RUN apt-get update && apt-get install -y --no-install-recommends \
   gcc \
   libc6-dev \