Copying build-dependent dlls to working directory with CMake - dll

Question

So, I've searched for a while through internet and I still have to find a satisfactory solution to the following:
I have a CMake project on Windows (actually, it should work on Linux too, but I guess it'll be almost the same, since the real issue comes from having multiple configurations: Release, Debug and Release_Debug).
I'm using several 3rd-party libraries, among others (just to make an example): pthread, openssl and qt.
Qt and openssl have their configuration scripts bundled with CMake, for pthread I've created an imported target with the following:
set_target_properties(pthread PROPERTIES
INTERFACE_INCLUDE_DIRECTORIES "${EXTERNAL_DIR}/pthread/include"
IMPORTED_IMPLIB_RELEASE "${EXTERNAL_DIR}/pthread/lib/pthreadVC3.lib"
IMPORTED_IMPLIB_DEBUG "${EXTERNAL_DIR}/pthread/lib/pthreadVC3d.lib"
IMPORTED_LOCATION_RELEASE "${EXTERNAL_DIR}/pthread/bin/pthreadVC3.dll"
IMPORTED_LOCATION_DEBUG "${EXTERNAL_DIR}/pthread/bin/pthreadVC3d.dll"
MAP_IMPORTED_CONFIG_RELEASE_DEBUG Release)
Everything compiles and links fine, but when it comes to run the application I need to copy the dlls into my working directory.
Currently, I'm doing it this way:
get_filename_component(QT_DLL_DIR ${QT_QMAKE_EXECUTABLE} DIRECTORY)
set(THIRD_PARTY_BINARIES
"${EXTERNAL_DIR}/pthread/bin/pthreadVC3$<$<CONFIG:Debug>:d>.dll"
"${EXTERNAL_DIR}/openssl/bin/libcrypto-1_1-x64.dll"
"${EXTERNAL_DIR}/openssl/bin/libssl-1_1-x64.dll"
"${QT_DLL_DIR}/QtCore$<$<CONFIG:Debug>:d>${QT_VERSION_MAJOR}.dll"
"${QT_DLL_DIR}/QtGui$<$<CONFIG:Debug>:d>${QT_VERSION_MAJOR}.dll")
foreach(BINARY ${THIRD_PARTY_BINARIES})
add_custom_command(TARGET MyApp POST_BUILD COMMAND ${CMAKE_COMMAND} -E copy_if_different "$<SHELL_PATH:${BINARY}>" "$<SHELL_PATH:${OUTPUT_DIR}/$<CONFIG>>")
endforeach()
As you can see, a lot of insight about dll naming (version number, platform, debug information and whatsoever) is hardcoded in these lines.
In fact, I already set myself the dll paths for pthread target, so why should I do that again?
Manually getting each target property seems a bit cumbersome to me, but taking into account several configurations makes things almost impossible: I can only use generator expressions inside add_custom_command(), so I don't have any clue on how to do all this in a compact and elegant way.
Additionally, I tried the following:
get_target_property(PTHREAD_LOCATION pthread LOCATION)
message("pthread: ${PTHREAD_LOCATION}")
get_target_property(OPENSSL_LOCATION OpenSSL::SSL LOCATION)
message("openssl: ${OPENSSL_LOCATION}")
get_target_property(QT_LOCATION Qt4::QtCore LOCATION)
message("qt: ${QT_LOCATION}")
And got the following output:
pthread: pthread-NOTFOUND
openssl: D:/workspace/ewas_win_2015/externals/openssl/lib/libssl.lib
qt: D:/local/qt/qt-4.8.7/lib/QtCore4.lib
I tried the same with LOCATION_RELEASE and got the following:
pthread: D:/workspace/ewas_win_2015/externals/pthread/bin/pthreadVC3.dll
openssl: D:/workspace/ewas_win_2015/externals/openssl/lib/libssl.lib
qt: D:/local/qt/qt-4.8.7/lib/QtCore4.lib
And with LOCATION_DEBUG:
pthread: D:/workspace/ewas_win_2015/externals/pthread/bin/pthreadVC3d.dll
openssl: D:/workspace/ewas_win_2015/externals/openssl/lib/libssl.lib
qt: D:/local/qt/qt-4.8.7/lib/QtCored4.lib
Then I switched to IMPORTED_LOCATION:
pthread: PTHREAD_LOCATION-NOTFOUND
openssl: D:/workspace/ewas_win_2015/externals/openssl/lib/libssl.lib
qt: QT_LOCATION-NOTFOUND
And to IMPORTED_LOCATION_RELEASE:
pthread: D:/workspace/ewas_win_2015/externals/pthread/bin/pthreadVC3.dll
openssl: D:/workspace/ewas_win_2015/externals/openssl/lib/libssl.lib
qt: D:/local/qt/qt-4.8.7/lib/QtCore4.lib
And finally to IMPORTED_LOCATION_DEBUG:
pthread: D:/workspace/ewas_win_2015/externals/pthread/bin/pthreadVC3d.dll
openssl: OPENSSL_LOCATION-NOTFOUND
qt: D:/local/qt/qt-4.8.7/lib/QtCored4.lib
I've read somewhere that the dll path is supposed to be in LOCATION (or IMPORTED_LOCATION) property, but apparently it's not the case for openssl and qt.
Moreover, each library seems to behave its own way. How am I supposed to do this programmatically (also for other 3rd-party libraries that I may have in my project)?
Thanks in advance.