No need to install LLD on travis/appveyor anymore

Rust now ships a LLD binary.

.travis.yml

@@ -19,29 +19,12 @@ os:
   - linux
   - osx
 
-addons:
-  apt:
-    sources:
-      - llvm-toolchain-trusty-5.0
-    packages:
-      - lld-5.0
-
 cache:
   directories:
     - $HOME/.cargo
     - $HOME/.xargo
     - $TRAVIS_BUILD_DIR/target
 
-before_install:
-  - |
-    if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-      set -e
-      LLVM_URL="https://releases.llvm.org/5.0.1/clang+llvm-5.0.1-x86_64-apple-darwin.tar.xz"
-      travis_retry wget -O llvm.tar.xz -nv ${LLVM_URL}
-      tar -xJ -f llvm.tar.xz
-      export PATH="`pwd`/clang+llvm-5.0.1-final-x86_64-apple-darwin/bin:$PATH"
-    fi
-
 before_script:
   - rustup component add rust-src
   - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)