[CPP] Remove libboost_system dependency

[asfimport]

Arrow added an additional libboost_system dependency. We now transitively added the dependency to parquet for static linking. Remove it from Parquet when Arrow does ARROW-1536

Reporter: Deepak Majeti / @majetideepak
Assignee: Deepak Majeti / @majetideepak

Related issues:

• [C++] Do not transitively depend on libboost_system (depends upon)

_{Note: This issue was originally created as PARQUET-1105. Please see the migration documentation for further details.}

[asfimport]

Uwe Korn / @xhochy:
Issue resolved by pull request 406
apache/parquet-cpp#406