Makefile build doesn't support DESTDIR convention

[craigbarnes]

The gmake build currently doesn't allow the common convention of make install DESTDIR=mybuildroot.

[geoffmcl]

As you may know the latest development branch is develop-500...
$ git checkout develop-500
This uses cmake and the install directory can be set by -
$ cd build/cmake
$ cmake ../.. -DCMAKE_INSTALL_PREFIX:PATH=/install/path
$ make install
so I hope this can be closed?