Don't run Travis CI when modifying appveyor.yml and don't run Appveyo…

…r when modifying .travis.yml (#231)

.travis.yml

@@ -103,7 +103,12 @@ matrix:
         - CLANG_CXX=clang++
         - LLVM_CONFIG=llvm-config
         - DEPLOY=1
-
+before_install:
+    - |
+      git diff --name-only $TRAVIS_COMMIT_RANGE | grep -qvE '^appveyor.yml$' || {
+        echo "Only appveyor.yml was updated, stopping build process."
+        exit
+      }
 install:
     - if [ "$TRAVIS_OS_NAME" = "osx" ]; then sudo softwareupdate -i "Command Line Tools (macOS High Sierra version 10.13) for Xcode-9.4"; fi
     - if [ "$TRAVIS_OS_NAME" = "osx" ]; then brew cask uninstall --force oclint; fi

appveyor.yml

@@ -2,6 +2,10 @@ image: Visual Studio 2017
 platform:
 - x64
 
+skip_commits:
+  files:
+    - .travis.yml
+
 environment:
   matrix:
     - CHANNEL: stable