debug/gdb: remove ncurses cleanup

That's legacy code that was usefull when ncurses was installed
in the sysroot. Still it's not longer the case (it's installed
in a special dedicated directory), we can remove that piece of
code.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 reporter_name="Ioannis E. VENETIS"

 reporter_url="http://sourceware.org/ml/crossgcc/2009-11/msg00109.html"

 reporter_comment=""