Add proper quoting for CI config.

azure-pipelines.yml

@@ -18,9 +18,10 @@ jobs:
           BuildType: Release
     steps:
     - script: |
-        sudo add-apt-repository deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main
+        sudo add-apt-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main"
         sudo apt-get update
-        sudo apt-get install -y ninja-build clang-8
+        sudo apt-get install -y ninja-build
+        sudo apt-get install -y clang-8
 
     - task: CMake@1
       inputs: