Fall back to wide-char versions of lib{ncurses,panel} on load failure

[ackalker]

On some systems, libncurses.so and libpanel.so are linker scripts rather than actual binaries. Trying to load these libraries in Julia produces errors, as Julia currently doesn't know how to handle such linker scripts,

Work around this issue by trying the most common redirections specified by linker scripts:

libncurses.so -> libncursesw.so libpanel.so -> libpanelw.so