Hi,
There is an (apparently intentional) underlinking issue in readline. With readline 6.2 you could workaround that breakage with:
make install SHLIB_LIBS=-lncurses
With 6.3 it will run a new instance of make (eg make -C shlib) and drop the overridden SHLIB_LIBS and thus enforcing the underlnking.
The underlinking is wrong for many reasons, and with some modern libcs like musl libc it will simply not work. I have studied the
configure.ac script too but there are apparently no way to override underlinking and for linking to ncurses (or termcap).
It would be nice to be able to override the linker flags.