Travis: llvm, additional packages and container

Additionally use clang as a compiler, versions 3.8, 3.9 and 4.0

Additionally use gcc/g++-7

Add additional packages used by build now that they are whitelisted.
      - libsnappy-dev       - innodb compression
      - liblzma-dev         - innodb compression
      - libzmq-dev          - used my Mgoonga
      - libdistro-info-perl - used by autobake-debian

Change to a container build as they tend to have more ram
Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

.travis.compiler.sh

+#!/bin/sh
+if [[ "${TRAVIS_OS_NAME}" == 'linux' && "${CXX}" == 'clang++' ]]; then
+  case ${GCC_VERSION} in
+    4.8) MYSQL_BUILD_CXX=clang++-3.8;;
+    5) MYSQL_BUILD_CXX=clang++-3.9;;
+    6) MYSQL_BUILD_CXX=clang++-4.0;;
+  esac
+  export MYSQL_BUILD_CXX MYSQL_BUILD_CC=${MYSQL_BUILD_CXX/++/}
+elif [[ "${TRAVIS_OS_NAME}" == 'linux' && "${CXX}" == 'g++' ]]; then
+  export MYSQL_BUILD_CXX=g++-${GCC_VERSION};
+  export MYSQL_BUILD_CC=gcc-${GCC_VERSION}
+fi

.travis.yml

 # vim ft=yaml
 # travis-ci.org definition
 
-# non-container builds don't have enough RAM to reliably compile
-sudo: required
+sudo: false
 dist: trusty
 
 language: cpp
+os:
+  - linux
 compiler:
   - gcc
+  - clang
 cache:
   - apt
   - ccache
@@ -17,21 +19,25 @@ env:
     - GCC_VERSION=4.8
     - GCC_VERSION=5
     - GCC_VERSION=6
+
 addons:
   apt:
     sources:
       - ubuntu-toolchain-r-test
-# below requires https://github.com/travis-ci/apt-source-whitelist/pull/309
-#      - llvm-toolchain-trusty-3.8
-#      - llvm-toolchain-trusty-3.9
-# llvm urls awaiting fix
-# https://github.com/travis-ci/apt-source-whitelist/pull/288
-# https://github.com/travis-ci/apt-source-whitelist/pull/309
+      - llvm-toolchain-trusty
+      - llvm-toolchain-trusty-3.9
+      - llvm-toolchain-trusty-4.0
     packages: # make sure these match debian/control contents
       - gcc-5
       - g++-5
       - gcc-6
       - g++-6
+      - clang-3.8
+      - llvm-3.8-dev
+      - clang-3.9
+      - llvm-3.9-dev
+      - clang-4.0
+      - llvm-4.0-dev
       - bison
       - chrpath
       - cmake
@@ -57,18 +63,23 @@ addons:
       - zlib1g-dev
       - libcrack2-dev
       - libjemalloc-dev
+      - libsnappy-dev
+      - liblzma-dev
+      - libzmq-dev
+      - libdistro-info-perl
       - devscripts # implicit for any build on Ubuntu
 
-# libsnappy-dev # https://github.com/travis-ci/apt-package-whitelist/issues/3880
-# liblzma-dev # https://github.com/travis-ci/apt-package-whitelist/issues/3879
-# libzmq-dev # https://github.com/travis-ci/apt-package-whitelist/issues/3881
 # libsystemd-daemon-dev # https://github.com/travis-ci/apt-package-whitelist/issues/3882
 
 script:
-  - export MYSQL_BUILD_CC=/usr/bin/gcc-${GCC_VERSION} MYSQL_BUILD_CXX=/usr/bin/g++-${GCC_VERSION}
+  - source .travis.compiler.sh
   - ${MYSQL_BUILD_CC} --version ; ${MYSQL_BUILD_CXX} --version
   - cd "${TRAVIS_BUILD_DIR}"
+# https://github.com/travis-ci/travis-ci/issues/7062 - /run/shm isn't writable or executable
+# in trusty containers
+  - export MTR_MEM=/tmp
   - env DEB_BUILD_OPTIONS="parallel=3" debian/autobake-deb.sh;
+  - ccache --show-stats
 
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