travis.yml: added clang-3.9 and clang-4.0 tests

Author: inikep

.travis.yml

@@ -135,7 +135,7 @@ matrix:
         apt:
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.5
+            - llvm-toolchain-trusty-3.5
           packages:
             - clang-3.5
       env: CC_COMPILER=clang-3.5 CXX_COMPILER=clang++-3.5
@@ -146,7 +146,7 @@ matrix:
         apt:
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.6
+            - llvm-toolchain-trusty-3.6
           packages:
             - clang-3.6
       env: CC_COMPILER=clang-3.6 CXX_COMPILER=clang++-3.6
@@ -157,11 +157,33 @@ matrix:
         apt:
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.8
+            - llvm-toolchain-trusty-3.8
           packages:
             - clang-3.8
       env: CC_COMPILER=clang-3.8 CXX_COMPILER=clang++-3.8
 
+    - dist: trusty
+      sudo: required
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-trusty-3.9
+          packages:
+            - clang-3.9
+      env: CC_COMPILER=clang-3.9 CXX_COMPILER=clang++-3.9
+
+    - dist: trusty
+      sudo: required
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-trusty-4.0
+          packages:
+            - clang-4.0
+      env: CC_COMPILER=clang-4.0 CXX_COMPILER=clang++-4.0
+
 script:
   - $CC_COMPILER -v
   - $CXX_COMPILER -v