Cmake doesn't take into consideration value of -hostprefix

When building Qt, you can specify where you would like host tools too be installed, like qmake, moc, rcc, etc by using the -hostprefix configuration argument. This makes sense when cross-compiling because these tools are built for the host system (ex x86_64). That way the libraries are cross compiled for whatever arch/system, and installed into the -prefix (sysroot), and host tools are installed else where.

The problem is that the generated cmake files define the location of the host tools relative to their own location.

get_filename_component(_qt5_corelib_install_prefix "${CMAKE_CURRENT_LIST_DIR}/../../../" ABSOLUTE)

if (NOT TARGET Qt5::qmake)
    add_executable(Qt5::qmake IMPORTED)

    set_target_properties(Qt5::qmake PROPERTIES
        IMPORTED_LOCATION "${_qt5_corelib_install_prefix}/bin/qmake"
    )
endif()

if (NOT TARGET Qt5::moc)
    add_executable(Qt5::moc IMPORTED)

    set_target_properties(Qt5::moc PROPERTIES
        IMPORTED_LOCATION "${_qt5_corelib_install_prefix}/bin/moc"
    )
    # For CMake automoc feature
    get_target_property(QT_MOC_EXECUTABLE Qt5::moc LOCATION)
endif()

This location is inside of the -prefix location, which will place moc within the sysroot. When -hostprefix has been defined during configuration, moc wont exist in this hard-coded location, so when these macro files are generated they need to take into consideration the value of -hostprefix.