debug/gdb: chmod ncurses files to u+w

The ncurses-5.7 tarball contains only RO files.
We have to chmod them u+w.

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

reporter_name="Julien DUSSER"

reporter_url="http://sourceware.org/ml/crossgcc/2008-10/msg00054.html"

reporter_comment="Soft-float for the 405 PowerPC"