Travis: Update clang-format to version 8.0

.travis.yml

@@ -23,9 +23,9 @@ matrix:
       addons:
         apt:
           sources:
-            - llvm-toolchain-xenial-6.0
+            - llvm-toolchain-xenial-8
           packages:
-            - clang-format-6.0
+            - clang-format-8
 
     - env: PLATFORM=x11 TOOLS=yes TARGET=debug CACHE_NAME=${PLATFORM}-tools-mono-gcc-8 MATRIX_EVAL="CC=gcc-8 && CXX=g++-8" EXTRA_ARGS="module_mono_enabled=yes mono_glue=no warnings=extra werror=yes"
       os: linux

misc/travis/clang-format.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-CLANG_FORMAT=clang-format-6.0
+CLANG_FORMAT=clang-format-8
 
 if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then
     # Check the whole commit range against $TRAVIS_BRANCH, the base merge branch