travis: try to fix build

Author: emilio

.travis.yml

@@ -1,22 +1,28 @@
 language: rust
-addons:
-    apt:
-      sources:
-        - llvm-toolchain-precise-3.8
-        - ubuntu-toolchain-r-test
-      packages:
-        - libclang-3.8-dev
-        - llvm-3.8-dev
+matrix:
+  include:
+    - os: linux
+      d: ldc
+      env: LLVM_VERSION=3.8.0
 env:
   - LLVM_VERSION=3.8
+
 rust:
   - nightly
 cache:
   directories:
+    - llvm-3.8.0
     - $HOME/.cargo
 
 before_install:
   -
+    if [ "${TRAVIS_OS_NAME}" = "linux" ]; then
+      if [ -z "$(ls -A llvm-$LLVM_VERSION)" ]; then
+        wget -O llvm-$LLVM_VERSION.tar.xz http://llvm.org/releases/$LLVM_VERSION/clang+llvm-$LLVM_VERSION-x86_64-linux-gnu-ubuntu-14.04.tar.xz;
+        mkdir llvm-$LLVM_VERSION;
+        xzcat llvm-$LLVM_VERSION.tar.xz | tar -xvf - --strip 1 -C llvm-$LLVM_VERSION;
+      fi;
+    fi
     if [ "${TRAVIS_OS_NAME}" = "osx" ]; then
       if [ "${LLVM_VERSION}" != "devtools" ]; then
         brew update >/dev/null;
@@ -27,7 +33,9 @@ before_install:
 before_script:
   -
     if [ "${TRAVIS_OS_NAME}" = "linux" ]; then
-      export LIBCLANG_PATH=/usr/lib/llvm-${LLVM_VERSION}/lib;
+      llvm-$LLVM_VERSION/bin/llvm-config --version;
+      export LLVM_CONFIG="llvm-$LLVM_VERSION/bin/llvm-config";
+      export LIBCLANG_PATH=llvm-$LLVM_VERSION/lib;
     elif [ "${TRAVIS_OS_NAME}" = "osx" ]; then
       if [ "${LLVM_VERSION}" = "devtools" ]; then
         export LIBCLANG_PATH=/Library/Developer/CommandLineTools/usr/lib;