FindBoost: Add support for Boost 1.65.0 and 1.65.1 to CMake 3.9

Brad Kingrequested to merge
brad.king/cmake:backport-FindBoost-1.65 into master

Backport the changes from !1172 (merged) and !1241 (merged) to CMake 3.9.

Fixes: #17289 (closed)

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