package/ncurses: trim leading 'lib' from definition of libs to install

Currently, ncurses creates symlinks from the non-'w' variants to the
equivalent 'w' variant, but forgets to do so for pkg-config files.

To be able to share the same list between the libraries and the
pkg-config files to symlink, just trim the 'lib' prefix of libraries in
the definition, and just add it back at the time we need it.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>