Remove linux tests from travis.

These tests are already covered by jenkins and right now jenkins can
finish these tests much quicker then travis.

Change-Id: I5799761ccc338211d750940e3cf4c8e2569c8144

.travis.yml

@@ -5,7 +5,6 @@ sudo: required
 # rvm/gemfile/jdk/etc. entries rather than manually doing the work.
 language: cpp
 os:
-  - linux
   - osx
 # The Objective C build needs Xcode 7.0 or later.
 osx_image: xcode7.3
@@ -47,16 +46,6 @@ matrix:
     # which doesn't work on OS X.
     - os: osx
       env: CONFIG=golang
-    # OS X/iOS tests of Objective C (needs Xcode, so it won't work on other
-    # platforms).
-    - os: linux
-      env: CONFIG=objectivec_ios_debug
-    - os: linux
-      env: CONFIG=objectivec_ios_release
-    - os: linux
-      env: CONFIG=objectivec_osx
-    - os: linux
-      env: CONFIG=objectivec_cocoapods_integration
   # The dotnet environment requires Ubuntu 14.04 or 16.04. This
   # configuration is effectively an "extra" one, outside the
   # autogenerated matrix.

jenkins/pull_request_in_docker.sh

@@ -48,6 +48,7 @@ $TIME_CMD $TEST_SCRIPT cpp > >(tee $CPP_STDOUT) 2> >(tee $CPP_STDERR >&2)
 # Other tests are run in parallel.
 
 parallel --results $LOG_OUTPUT_DIR --joblog $OUTPUT_DIR/joblog $TEST_SCRIPT ::: \
+  cpp_distcheck \
   csharp \
   java_jdk7 \
   javanano_jdk7 \