Travis: Use clang-format 8 instead of 6

Fix bogus build matrix due to stray quotes.

.travis.yml

@@ -19,10 +19,10 @@ matrix:
     - env: STATIC_CHECKS=yes
       os: linux
       compiler: gcc
-    - env: GODOT_TARGET=x11 TOOLS=yes CACHE_NAME=${GODOT_TARGET}-gcc-tools"
+    - env: GODOT_TARGET=x11 TOOLS=yes CACHE_NAME=${GODOT_TARGET}-gcc-tools
       os: linux
       compiler: gcc
-    - env: GODOT_TARGET=x11 TOOLS=no CACHE_NAME=${GODOT_TARGET}-clang"
+    - env: GODOT_TARGET=x11 TOOLS=no CACHE_NAME=${GODOT_TARGET}-clang
       os: linux
       compiler: clang
     - env: GODOT_TARGET=android TOOLS=no CACHE_NAME=${GODOT_TARGET}-gcc
@@ -44,7 +44,7 @@ addons:
   apt:
     sources:
       - ubuntu-toolchain-r-test
-      - llvm-toolchain-trusty-6.0
+      - llvm-toolchain-trusty-8
     packages:
       - build-essential
       - scons
@@ -61,8 +61,7 @@ addons:
       - libssl-dev
 
       # For style checks.
-      - clang-format-6.0
-      - libstdc++6 # >= 4.9 needed for clang-format-6.0
+      - clang-format-8
 
 before_install:
   - if [ "$STATIC_CHECKS" = "yes" ]; then

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
     # Travis only clones the PR branch and uses its HEAD commit as detached HEAD,