package/wireshark: fix kconfig dependencies

package/wireshark: fix kconfig dependencies

Commit fa6feff (wireshark: needs the qt5tools lrelease utility)
introduced a circular dependency chain in Kconfig:

    package/qt5/qt5base/Config.in:118:error: recursive dependency detected!
    package/qt5/qt5base/Config.in:118:      symbol BR2_PACKAGE_QT5BASE_GUI is selected by BR2_PACKAGE_QT5TOOLS_PIXELTOOL
    package/qt5/qt5tools/Config.in:19:      symbol BR2_PACKAGE_QT5TOOLS_PIXELTOOL depends on BR2_PACKAGE_QT5TOOLS
    package/qt5/qt5tools/Config.in:1:       symbol BR2_PACKAGE_QT5TOOLS is selected by BR2_PACKAGE_QT5BASE_WIDGETS
    package/qt5/qt5base/Config.in:131:      symbol BR2_PACKAGE_QT5BASE_WIDGETS is selected by BR2_PACKAGE_QT5X11EXTRAS
    package/qt5/qt5x11extras/Config.in:1:   symbol BR2_PACKAGE_QT5X11EXTRAS depends on BR2_PACKAGE_QT5BASE_XCB
    package/qt5/qt5base/Config.in:186:      symbol BR2_PACKAGE_QT5BASE_XCB depends on BR2_PACKAGE_QT5BASE_GUI

Fix that by dropping the select on the Qt5Tools, and introduce an
intermediate kconfig-level variable to represent the new condition, to
simplify the .mk file.

That would make the condition for enabling/disabling the GUI to be a
little bit more complex by adding yet another (long-ish) variable.

So we also introduce an intermediate kconfig-level variable that
represent the condition to enable the GUI.

Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Baruch Siach <baruch@tkos.co.il>
Tested-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>