OpenBSD needs -lcurses

[sjmulder]

On OpenBSD 6.4-STABLE, compilation of master fails:

$ gmake
cc -O3 -Wall -Wextra -Wno-unused-parameter -Werror -Iinc -o bcal src/bcal.c -lreadline
/usr/bin/../lib/libreadline.so.4.0: undefined reference to `tgetnum'
/usr/bin/../lib/libreadline.so.4.0: undefined reference to `tgoto'
/usr/bin/../lib/libreadline.so.4.0: undefined reference to `tgetflag'
/usr/bin/../lib/libreadline.so.4.0: undefined reference to `tputs'
/usr/bin/../lib/libreadline.so.4.0: undefined reference to `tgetent'
/usr/bin/../lib/libreadline.so.4.0: undefined reference to `tgetstr'

Adding -lcurses fixes the issue:

$ gmake LDLIBS="-lreadline -lcurses"
cc -O3 -Wall -Wextra -Wno-unused-parameter -Werror -Iinc -o bcal src/bcal.c -lreadline -lcurses
$

Not sure if it's safe to add -lcurses by default.

[jarun]

Now that you have made LDLIBS flexible, I think you can take care of this downstream. bcal doesn't use ncurses.

[sjmulder]

It's readline that uses the functions. Odd because readline is used on every platform and OpenBSD uses GNU readline like everyone else.

In any case if you don't feel good about including it here I'll do it downstream.