consider warnings from the source compilation [LUCENE-3161]

as Doron mentioned in his review: At compiling there are various warning printed, I think it would be more assuring for downloaders if the build runs without warning. These warnings are not a stopper.

we could conditionalize these warnings so that they don't "display" when compiling from actual releases, but I have to wonder if we should hide these... being open source I think we should display all our warts, maybe some contributor sees these warnings and decides they want to submit a patch to fix some of them.

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Migrated from [LUCENE-3161](https://issues.apache.org/jira/browse/LUCENE-3161) by Robert Muir (@rmuir), updated May 09 2016

Start by reproducing a source compilation and recording the warnings it prints. Read the build configuration and compilation entry points to determine whether the warnings should be fixed or conditionally hidden for release builds. Done means the warning policy is implemented and the source compilation behavior is verified.

Written by the indexing model from the issue text.