Make sure that the include files are copied everytime make is written.

[toshal-a]

While reviewing a PR I noticed a bug.

Whenever a user hits make two times consecutively while building the repository, if there is any change in the include directory, the given change is not reflected and make does not build that change. The reason might be because the build/include once created by copying the include folder, then the changes are not reflected.

Steps to Reproduce

mkdir build && cd ./build
cmake ../
make 
Then make some changes in any file (For example, in `summary_writer_impl.hpp` change the method name.)
make

Actual Behaviour

The changes made in summary_writer_impl.hpp are not getting reflected while building and the build compiles as normal.

Expected Behaviour

The changes should get reflected.

[jeffin143]

After making changes hit cmake again and then hit make , it will work

[jeffin143]

Currently the include dir is only build , so if we want to replicate what is done in mlpack the include dir should be ../include and then the changes would be reflected when you hit make