Run tests with more versions of libclang

First, update our existing 3.8.X and 3.9.X libclang testing versions to their
latest point releases. Second, add testing on the latest 3.7.X release and the
latest 4.0.X release.

Author: fitzgen

.travis.yml

@@ -14,8 +14,19 @@ rust:
   - stable
 
 env:
-  - CARGO_TARGET_DIR=/tmp/bindgen LLVM_VERSION=3.8 BINDGEN_FEATURES=testing_only_llvm_stable
-  - CARGO_TARGET_DIR=/tmp/bindgen LLVM_VERSION=3.9 BINDGEN_FEATURES=
+  global:
+    - CARGO_TARGET_DIR=/tmp/bindgen
+  matrix:
+    - LLVM_VERSION=3.7.1 BINDGEN_FEATURES=testing_only_llvm_stable
+    - LLVM_VERSION=3.8.1 BINDGEN_FEATURES=testing_only_llvm_stable
+    - LLVM_VERSION=3.9.0 BINDGEN_FEATURES=
+    - LLVM_VERSION=4.0.0 BINDGEN_FEATURES=
+
+matrix:
+  fast_finish: true
+  allow_failures:
+    - env: LLVM_VERSION=4.0.0 BINDGEN_FEATURES=
+    - env: LLVM_VERSION=3.7.1 BINDGEN_FEATURES=testing_only_llvm_stable
 
 cache:
   directories:

ci/before_install.sh

@@ -1,21 +1,13 @@
-set -e
+set -ex
 pushd ~
 
 # Workaround for Travis CI macOS bug (https://github.com/travis-ci/travis-ci/issues/6307)
 if [ "${TRAVIS_OS_NAME}" == "osx" ]; then
     rvm get head || true
 fi
 
-function llvm_version_triple() {
-    if [ "$1" == "3.8" ]; then
-        echo "3.8.0"
-    elif [ "$1" == "3.9" ]; then
-        echo "3.9.0"
-    fi
-}
-
 function llvm_download() {
-    export LLVM_VERSION_TRIPLE=`llvm_version_triple ${LLVM_VERSION}`
+    export LLVM_VERSION_TRIPLE="${LLVM_VERSION}"
     export LLVM=clang+llvm-${LLVM_VERSION_TRIPLE}-x86_64-$1
 
     wget http://llvm.org/releases/${LLVM_VERSION_TRIPLE}/${LLVM}.tar.xz