CI: prepare for travis

[Akim Demaille]

I cannot continue without some CI, there are too many
different behaviors depending on the compiler and compiler
version.  It takes too much time on my machine, and I often
forget this or that compiler.  I have been caught many times
by portability issues when working for move semantics.

This is just the start, we should add more checks
(‘maintainer check’).  I have ‘forked’ Bison on my github
account (https://github.com/akimd/bison), and the builds are
launched from there.  They can be watched here:
https://travis-ci.com/akimd/bison.


commit 7132650bba7e2c357c96fdb86aa764651e151877
Author: Akim Demaille <address@hidden>
Date:   Thu Sep 6 05:55:14 2018 +0200

    CI: prepare for travis
    
    * .travis.yml: New.

diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 00000000..b21839ea
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,128 @@
+language: cpp
+
+matrix:
+  include:
+    # works on Precise and Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-4.9
+      env:
+         - MATRIX_EVAL="CC=gcc-4.9 && CXX=g++-4.9"
+
+    # works on Precise and Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-5
+      env:
+         - MATRIX_EVAL="CC=gcc-5 && CXX=g++-5"
+
+    # works on Precise and Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-6
+      env:
+        - MATRIX_EVAL="CC=gcc-6 && CXX=g++-6"
+
+    # works on Precise and Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-7
+      env:
+        - MATRIX_EVAL="CC=gcc-7 && CXX=g++-7"
+    # works on Precise and Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-precise-3.6
+          packages:
+            - clang-3.6
+      env:
+        - MATRIX_EVAL="CC=clang-3.6 && CXX=clang++-3.6"
+
+    # works on Precise and Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-precise-3.7
+          packages:
+            - clang-3.7
+      env:
+        - MATRIX_EVAL="CC=clang-3.7 && CXX=clang++-3.7"
+
+    # works on Precise and Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-precise-3.8
+          packages:
+            - clang-3.8
+      env:
+        - MATRIX_EVAL="CC=clang-3.8 && CXX=clang++-3.8"
+
+    # works on Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - llvm-toolchain-trusty-3.9
+          packages:
+            - clang-3.9
+      env:
+        - MATRIX_EVAL="CC=clang-3.9 && CXX=clang++-3.9"
+
+    # works on Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - llvm-toolchain-trusty-4.0
+          packages:
+            - clang-4.0
+      env:
+        - MATRIX_EVAL="CC=clang-4.0 && CXX=clang++-4.0"
+
+    # works on Trusty
+    - os: linux
+      addons:
+        apt:
+          sources:
+            - llvm-toolchain-trusty-5.0
+          packages:
+            - clang-5.0
+      env:
+        - MATRIX_EVAL="CC=clang-5.0 && CXX=clang++-5.0"
+
+
+before_install:
+  - sudo apt-get update -qq
+  - sudo apt-get install -qq autoconf automake autopoint flex gettext graphviz 
help2man m4 texinfo valgrind
+  - eval "${MATRIX_EVAL}"
+
+script:
+  - ./bootstrap
+  - ./configure CC="$CC" CXX="$CXX"
+  - make -j2
+  - make check VERBOSE=1 TESTSUITEFLAGS=-j2
+