[CMake] Copying files and including them in a CPack archive

[Chris Wood]

So, there are numerous ways to copy files (and directories) at CMake
runtime (file(COPY ...), configure_file(...) and add_custom_command()
all work*), but I haven't yet found out how to make a file or
directory copied from the source to build directory appear in an
archive generated by CPack. I thought that this Stack Overflow answer
[1] would fix it, as it actually links the copying to a target which
will then have an install linked to it:

install(TARGET mytarget DESTINATION bin)

whereas I did recognise that the file() and configure_file() commands
don't have an obvious way to be added to a target. But, this didn't
work. So, given a simple CMakeLists.txt, such as the one below, how do
I make all of the files (including the exmaple directory) appear in
the archive?!

cmake_minimum_required(VERSION 2.6 FATAL_ERROR)
enable_language(FORTRAN)
add_executable(mytarget ${PROJECT_SOURCE_DIR}/myprog.for)
install(TARGETS mytarget DESTINATION bin)

add_custom_command(TARGET mytarget PREBUILD
                COMMAND ${CMAKE_COMMAND} -E copy_directory
                  ${PROJECT_SOURCE_DIR}/examplefiles
${PROJECT_BINARY_DIR}/examplefiles)

set(CPACK_GENERATOR "TGZ")
include(CPack)

* I haven't yet found out which one of these 3 methods is actually
(most?) correct - so any advice on this too will be hugely appreciated

[1]: http://stackoverflow.com/a/10672739/889604