combined doxygen search for DRMF and DR API

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on August 17, 2014 11:05:42_

split from issue #1056 The current DR + DRMF + Dr. Memory combined package has separate documentation. We've added cross-links to our own custom pages, but the doxygen-generated API docs are completely separate. Furthermore, the top-level search will only search the DR API.

This issue covers a deeper integration, whether through a server-side combined search, a real combined doxygen processing into a single set of docs, or something else.

For now, can we add a note under the search box? I don't see an easy way
to do it.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=1609_