update clang-format to current stable version

azure-pipelines/clang-format-applied.yml

@@ -22,9 +22,9 @@ stages:
     steps:
     - bash: |
         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-8 main"
+        sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main"
         sudo apt-get update
-        sudo apt-get install -y clang-format-8
+        sudo apt-get install -y clang-format-9
       displayName: 'Install clang-format'
     - bash: |
         # Checkout the master branch as we require it to get the list of modified files

azure-pipelines/util/format_diff_lines.pl

@@ -13,7 +13,7 @@ my @hunks;
 # Current file
 my $current_file;
 
-my @CLANG_FMT_CMDS = ("clang-format", "clang-format-8");
+my @CLANG_FMT_CMDS = ("clang-format", "clang-format-9");
 my $clang_format_cmd = "";
 for my $c (@CLANG_FMT_CMDS) {
 	if (`$c --version`) {