PIG-5414 Fix the build for Linux ARM64

[martin-g]

More and more software deployment and deployment is being done on ARM64 CPU architecture. It would be good if Apache Pig is being regularly tested on ARM64.

https://cwiki.apache.org/confluence/display/PIG/HowToContribute mentions Jenkins job (https://builds.apache.org/job/Pig-trunk-commit) but it seems it got lost at some point.

Update Snappy because the old version does not provide native library for aarch64 (ARM64). Update Avro to 1.8.2 because otherwise TestAvroStorage and TestOrcStorage tests fail on Linux ARM64. Add TravisCI build config to run the build on Linux ARM64.

[martin-g]

JIRA ticket: https://issues.apache.org/jira/browse/PIG-5414

[emiliofernandes]

+1 for official support for ARM64!

[gancho-ivanov]

One more +1 for ARM64 support!