PARQUET-1296: Travis kills build after 10 minutes, because "no output…

… was received"

Use pv to periodically print progress for Travis to prevent timeout due to lack of output.

.travis.yml

@@ -3,6 +3,7 @@ before_install:
   - date
   - sudo apt-get update -qq
   - sudo apt-get install build-essential
+  - sudo apt-get install pv
   - date
   - mkdir protobuf_install
   - pushd protobuf_install
@@ -33,5 +34,5 @@ env:
   - HADOOP_PROFILE=default TEST_CODECS=uncompressed,brotli
   - HADOOP_PROFILE=default TEST_CODECS=gzip,snappy
 
-install: mvn install --batch-mode -DskipTests=true -Dmaven.javadoc.skip=true -Dsource.skip=true > mvn_install.log || (cat mvn_install.log && false)
+install: mvn install --batch-mode -DskipTests=true -Dmaven.javadoc.skip=true -Dsource.skip=true | pv -fbi 60 > mvn_install.log || (cat mvn_install.log && false)
 script: mvn test -P $HADOOP_PROFILE