[linux] Update target headless backends

Enable OSMesa backend via WITH_OSMESA=1 envvar.

OSMesa backend uses Gallium OSMesa implementation, which uses
LLVMpipe as default driver.

.travis.yml

@@ -6,7 +6,7 @@ addons_shortcuts:
   addons_clang35: &clang35
     apt:
       sources:  [ 'ubuntu-toolchain-r-test', 'george-edison55-precise-backports' ]
-      packages: [ 'clang-3.5', 'libstdc++-4.9-dev', 'libstdc++6', 'libllvm3.4', 'cmake', 'cmake-data',
+      packages: [ 'clang-3.5', 'libstdc++-4.9-dev', 'libstdc++6', 'libllvm3.8v4', 'cmake', 'cmake-data',
                   'mesa-utils', 'libxi-dev', 'libglu1-mesa-dev', 'x11proto-randr-dev', 'x11proto-xext-dev', 'libxrandr-dev',
                   'x11proto-xf86vidmode-dev', 'libxxf86vm-dev', 'libxcursor-dev', 'libxinerama-dev' ]
   addons_gcc5: &gcc5
@@ -46,7 +46,6 @@ before_script:
 script:
   - make linux
   - make benchmark
-  - make test
   - make run-test
 after_script:
   - ccache --show-stats
@@ -60,7 +59,7 @@ matrix:
       dist: trusty
       language: node
       compiler: "node4-clang35-debug"
-      env: _CXX=clang++-3.5 _CC=clang-3.5
+      env: _CXX=clang++-3.5 _CC=clang-3.5 WITH_OSMESA=1
       addons: *clang35
       before_script:
         - export PACKAGE_JSON_VERSION=$(node -e "console.log(require('./package.json').version)")

scripts/travis_setup.sh

@@ -30,16 +30,6 @@ ${CXX} --version
 # Ensure mason is on the PATH
 export PATH="`pwd`/.mason:${PATH}" MASON_DIR="`pwd`/.mason"
 
-# Start the mock X server
-if [ -f /etc/init.d/xvfb ] ; then
-    mapbox_time "start_xvfb" \
-    sh -e /etc/init.d/xvfb start
-    sleep 2 # sometimes, xvfb takes some time to start up
-fi
-
-# Make sure we're connecting to xvfb
-export DISPLAY=:99.0
-
 mapbox_time "checkout_mason" \
 git submodule update --init .mason
 
@@ -47,10 +37,20 @@ git submodule update --init .mason
 mapbox_time "touch_package_json" \
 touch package.json
 
-# Install and set up to load a more recent version of mesa
-mapbox_time "install_mesa" \
-mason install mesa 11.2.2
-export LD_LIBRARY_PATH="`mason prefix mesa 11.2.2`/lib:${LD_LIBRARY_PATH:-}"
+# Start the mock X server
+if [ -f /etc/init.d/xvfb ] && [ -z "${WITH_OSMESA}" ]; then
+    mapbox_time "start_xvfb" \
+    sh -e /etc/init.d/xvfb start
+    sleep 2 # sometimes, xvfb takes some time to start up
+
+    # Make sure we're connecting to xvfb
+    export DISPLAY=:99.0
+
+    # Install and set up to load a more recent version of mesa
+    mapbox_time "install_mesa" \
+    mason install mesa 11.2.2
+    export LD_LIBRARY_PATH="`mason prefix mesa 11.2.2`/lib:${LD_LIBRARY_PATH:-}"
+fi
 
 # Install and set up to load awscli
 pip install --user awscli