Give up on new making CI support recent clang-format.

Revert to 6.0 and use that locally to insert an extra blank line to make
CI happy...

azure-pipelines.yml

@@ -204,10 +204,10 @@ phases:
   steps:
   - script: |
       wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
-      sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-7.0 main"
+      sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-6.0 main"
       sudo apt-get update
-      sudo apt-get install -y clang-format-7.0
-      sudo update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-7.0 100
+      sudo apt-get install -y clang-format-6.0
+      sudo update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-6.0 100
 
       bash check-format.sh
 

src/mem/pagemap.h

@@ -348,5 +348,4 @@ namespace snmalloc
       } while (length > 0);
     }
   };
-
 }