kconfig: fix lists definition for C++
kconfig: fix lists definition for C++

The C++ compiler is more strict in that it refuses to assign
a void* to a struct list_head*.

Fix that by explicitly casting the poisonning constants.

(Tested with all 5 frontends, now.)

Reported-by: Randy Dunlap <6f29df8e90a57f1ba61ffd63b0468c86bb6d3a99@infradead.org>
Signed-off-by: "Yann E. MORIN" <b375a36861a21dce61868a5a9b415811d17b4e97@free.fr>
Cc: Randy Dunlap <6f29df8e90a57f1ba61ffd63b0468c86bb6d3a99@infradead.org>
Cc: Benjamin Poirier <88a09e5f2ee113c8016801accb3bb63c7cc88849@suse.de>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas