readline: Update to 8.0 and various fixes

readline: Update to 8.0 and various fixes

Update (lib)readline to 8.0
Remove autoreconf
Remove blankspace at the end of the lines in description
Remove --enable-shared and --enable-static as they're enabled by default
Remove TARGET_CPPFLAGS
Simplify install sections
Install readline.pc (pkgconfig)
Add patch for linking (lib)ncurses

Source:
https://git.buildroot.net/buildroot/plain/package/readline/0000-curses-link.patch

Signed-off-by: Daniel Engberg <daniel.engberg.lists@pyret.net>