Use Xenial repos

Author: TartanLlama

.travis.yml

@@ -98,7 +98,7 @@ matrix:
       addons:
         apt:
           sources:
-            - sourceline: "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-3.9 main"
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.9 main"
               key_url: "http://apt.llvm.org/llvm-snapshot.gpg.key"
             - ubuntu-toolchain-r-test
           packages:
@@ -109,7 +109,7 @@ matrix:
       addons:
         apt:
           sources:
-             - llvm-toolchain-trusty-4.0
+             - llvm-toolchain-xenial-4.0
              - ubuntu-toolchain-r-test
           packages:
              - clang++-4.0
@@ -119,7 +119,7 @@ matrix:
       addons:
         apt:
           sources:
-             - llvm-toolchain-trusty-5.0
+             - llvm-toolchain-xenial-5.0
              - ubuntu-toolchain-r-test
           packages:
              - clang++-5.0
@@ -129,7 +129,7 @@ matrix:
       addons:
         apt:
           sources:
-             - llvm-toolchain-trusty-6.0
+             - llvm-toolchain-xenial-6.0
              - ubuntu-toolchain-r-test
           packages:
              - clang++-6.0
@@ -212,7 +212,7 @@ matrix:
       addons:
         apt:
           sources:
-            - sourceline: "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-3.9 main"
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.9 main"
               key_url: "http://apt.llvm.org/llvm-snapshot.gpg.key"
             - ubuntu-toolchain-r-test
           packages:
@@ -223,7 +223,7 @@ matrix:
       addons:
         apt:
           sources:
-             - llvm-toolchain-trusty-4.0
+             - llvm-toolchain-xenial-4.0
              - ubuntu-toolchain-r-test
           packages:
              - clang++-4.0
@@ -233,7 +233,7 @@ matrix:
       addons:
         apt:
           sources:
-             - llvm-toolchain-trusty-5.0
+             - llvm-toolchain-xenial-5.0
              - ubuntu-toolchain-r-test
           packages:
              - clang++-5.0
@@ -243,7 +243,7 @@ matrix:
       addons:
         apt:
           sources:
-             - llvm-toolchain-trusty-6.0
+             - llvm-toolchain-xenial-6.0
              - ubuntu-toolchain-r-test
           packages:
              - clang++-6.0