Travis: Fix (still not sure there is a way to test those files). (#1044)

.travis.yml

@@ -29,4 +29,6 @@ script:
   - make -C examples/example_glfw_opengl2
   - make -C examples/example_glfw_opengl3
   - make -C examples/example_sdl_opengl3
-  - if [ $TRAVIS_OS_NAME == osx ]; then xcodebuild -project examples/example_apple_metal/example_apple_metal.xcodeproj -target example_apple_metal_macos;
+  - if [ $TRAVIS_OS_NAME == osx ]; then 
+      xcodebuild -project examples/example_apple_metal/example_apple_metal.xcodeproj -target example_apple_metal_macos;
+    fi