util-linux: fix host build when ncurses is not installed

util-linux: fix host build when ncurses is not installed

lib/colors.c uses HAVE_LIBTINFO to decide whether term.h and ncurses.h
should be included. However, the configure.ac check is bogus: it
checks for tinfo using pkg-config, and then if it fails, checks with
AC_CHECK_LIB(). So, if you have tinfo installed, but not the
corresponding development package, the pkg-config test will fail, but
the AC_CHECK_LIB test will succeed, even though the headers are not
available.

To address this, we explicitly tell host-util-linux that tinfo is not
available, like we're already doing for ncurses.

Fixes:

  http://autobuild.buildroot.net/results/3c447e601a7b728860e78cabf2191ab206e6480d/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>