debug/gdb: staticaly link to ncurses for the native gdb

Staticaly link the native gdb (the one that runs on the target,
not the cross one that runs on the host) to ncurses.

 # Compute Alpha-specific values

 CT_DoArchTupleValues () {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="${CT_ARCH}${CT_ARCH_ALPHA_VARIANT}"

 }