Bug#862390: ship CMake config files with the nlopt package

[slayoo]

Package: libnlopt-dev
Version: 2.4.2+dfsg-2

Building nlopt from source (https://github.com/stevengj/nlopt) using 
CMake causes "make install" to install CMake config files:

    $ sudo make install
    [ 88%] Built target nlopt
    [100%] Built target testopt
    Install the project...
    -- Install configuration: "Release"
    -- Up-to-date: /usr/lib/x86_64-linux-gnu/pkgconfig/nlopt.pc
    -- Up-to-date: /usr/include/nlopt.h
    -- Up-to-date: /usr/include/nlopt.hpp
    -- Up-to-date: /usr/include/nlopt.f
    -- Up-to-date: /usr/lib/x86_64-linux-gnu/libnlopt.so.0.9.0
    -- Up-to-date: /usr/lib/x86_64-linux-gnu/libnlopt.so.0
    -- Up-to-date: /usr/lib/x86_64-linux-gnu/libnlopt.so
    -- Up-to-date: 
/usr/lib/x86_64-linux-gnu/cmake/nlopt/NLoptLibraryDepends.cmake
    -- Up-to-date: 
/usr/lib/x86_64-linux-gnu/cmake/nlopt/NLoptLibraryDepends-release.cmake
    -- Up-to-date: 
/usr/lib/x86_64-linux-gnu/cmake/nlopt/NLoptConfig.cmake
    -- Up-to-date: 
/usr/lib/x86_64-linux-gnu/cmake/nlopt/NLoptConfigVersion.cmake
    -- Up-to-date: /usr/share/man/man3/nlopt.3
    -- Up-to-date: /usr/share/man/man3/nlopt_minimize.3
    -- Up-to-date: /usr/share/man/man3/nlopt_minimize_constrained.3

These *.cmake files enable CMake users to use find_package(NLopt) in 
their CMake scripts.
It would be great to ship these *.cmake files in the Debian package as 
well.

Thanks,
Sylwester