package/gptfdisk: propagate ncurses reverse dependency

gptfdisk cgdisk select nucurses wchar support which is disabled
on bfin with FLAT binary format.

Add the ncurses's reverse dependency to gptfdisk.

Fixes:
http://autobuild.buildroot.net/results/ce3/ce35c072f0b7c3a7a1918cb865a2eecbba8a1b23/



Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>