build-sys: make ncurses detection more robust

build-sys: make ncurses detection more robust

It seems Debina 8 is a little bit incompatible with us:

* ncurses-config is packaged in ncurses-bin where is *no* any
  development files! It means the script returns paths to not installed
  files (IMHO packaging bug)

  Fixed, we need to check for header files too.

* term.h is "everywhere" on Fedora:

	<term.h>
	<ncurses/term.h>
	<ncursesw/term.h>

  Debian is more strict and uses <ncurses[w]/term.h> only.

  Fixed, we need #ifdef storm to use the correct path

 * libtinfo-dev does not contains any header files

 Fixed, we have to always require installed ncurses devel stuff to compile,
 but we can link with -ltinfo only (cal, ul, more, ...)

 * we don't use termcap for more(1)

Signed-off-by: Karel Zak <kzak@redhat.com>