When deploying into some directory structure where CMAKE_INSTALL_LIBDIR
is different from Qt's lib dir, we need to set the RPATH of installed
plugins such that Qt libraries are found.
We do this using CMake's undocumented file(RPATH_SET) command and pray
that this command is safe to use across current and future CMake
versions. For CMake versions < 3.21, we use patchelf, which must be
installed on the host system.
The adjustment of rpaths can be turned on explicitly by setting
QT_DEPLOY_FORCE_ADJUST_RPATHS to ON.
The usage of patchelf can be forced by setting QT_DEPLOY_USE_PATCHELF to
ON regardless of the CMake version.
Change-Id: I62ced496b4c12bf6d46735d2af7ff35130148acb
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
5430fb2243