Travis: Add functionality to specify multiple make targets per test.

This allows us to better binpack the different tests across the 5 available Travis test slots.

.travis.yml

@@ -69,6 +69,7 @@ env:
     # As of 07/2015 this value works best in a Travis CI container.
     - VT_GO_PARALLEL=4
   matrix:
+    # NOTE: Use "" if you specify a space separated list of multiple targets.
     - MAKE_TARGET=java_vtgate_client_test
     - MAKE_TARGET=unit_test_goveralls
     - MAKE_TARGET=small_integration_test
@@ -86,8 +87,19 @@ script:
   - source dev.env
   # Log GOMAXPROCS (should be 2 as of 07/2015).
   - go run travis/log_gomaxprocs.go
+  # TODO(mberlin): Readd travis_retry when done testing.
   - |
-      travis_retry /usr/bin/time -f "CPU: %P Memory: %M kB" make build $MAKE_TARGET
+      return_value=1
+      for target in $MAKE_TARGET; do
+        echo "Running: make $target"
+        /usr/bin/time -f "elapsed: %E CPU: %P Memory: %M kB" make $target
+        return_value=$?
+        if [ $return_value -ne 0 ]; then
+          echo "ERROR: make $target failed with code: $return_value. Please fix the problem and re-trigger the test."
+          break
+        fi
+      done
+      [ $return_value -eq 0 ] || false
 after_failure:
   # In case of errors, output log files to make it easier to debug the error.
   # List all available files.