[boost] find_package(Boost) support

Subject: [boost] find_package(Boost) support
From: Peter Dimov (lists_at_[hidden])
Date: 2019-01-12 18:33:34

The current master and develop branches now install the necessary 
BoostConfig.cmake file (in $prefix/lib/cmake) such that f.ex. the CMake 
command

    find_package(Boost REQUIRED filesystem)

will find Boost 1.70 using the config file, rather than via FindBoost.cmake 
(*) (if the Boost installation prefix is in CMake's prefix search path.)

Interested parties are invited to test this support and share their 
experiences. Instead of a Git checkout, you can use the 1.70 release 
snapshots from https://dl.bintray.com/boostorg/master/ or 
https://dl.bintray.com/boostorg/develop/, as those better represent what the 
1.70 release will contain.

(*) Actually, the above command will invoke FindBoost.cmake, but FindBoost 
will look for a config file as a first step and use that, if found.

To disable FindBoost completely, use

    find_package(Boost CONFIG REQUIRED filesystem)

Or, on Windows, assuming the default C:\Boost installation,

    find_package(Boost REQUIRED filesystem PATHS C:/Boost)