TBR: i#2006 generalize drcachesim: refactor memref_t to use a union

Commit log for first patchset:
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i#2006 generalize drcachesim: refactor memref_t to use a union

Refactors memref_t, now that it is no longer a wire format, to use a union
to clarify which data is available for which type.
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[bruening, 2016-10-27 16:57:36]

Commit log for latest patchset:
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i#2006 generalize drcachesim: refactor memref_t to use a union

Refactors memref_t, now that it is no longer a wire format, to use a union
of structs to clarify which data is available for which type.

Review-URL: https://codereview.appspot.com/310640043
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[bruening, 2016-10-27 18:03:09]

Committed as
https://github.com/DynamoRIO/dynamorio/commit/96a6614d303ba63ef51416eedb105bf...

Final commit log: 
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i#2006 generalize drcachesim: refactor memref_t to use a union

Refactors memref_t, now that it is no longer a wire format, to use a union
of structs to clarify which data is available for which type.

Review-URL: https://codereview.appspot.com/310640043
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