add python2-dev to build-deps
add python2-dev to build-deps

Patch by brandonwilliams; reviewed by edimitrova for CASSANDRA-17871

adelapena/cassandra,jrwest/cassandra,blambov/cassandra,apache/cassandra,instaclustr/cassandra,instaclustr/cassandra,adelapena/cassandra,jrwest/cassandra,apache/cassandra,adelapena/cassandra,adelapena/cassandra,jrwest/cassandra,apache/cassandra,instaclustr/cassandra,apache/cassandra,jrwest/cassandra,blambov/cassandra,blambov/cassandra,instaclustr/cassandra,blambov/cassandra