Let configure fail if no terminal library is found

acinclude.m4

@@ -427,7 +427,9 @@ AC_ARG_WITH(termlib,
  AC_MSG_RESULT($with_termlib)
  test x"$with_termlib" = xyes && with_termlib="terminfo mytinfo termlib termcap tinfo ncurses curses"
  for lib in $with_termlib; do
-   AC_CHECK_LIB($lib, tgetent, [W3M_LIBS="$W3M_LIBS -l$lib"; break])
+   AC_CHECK_LIB($lib, tgetent,
+                [W3M_LIBS="$W3M_LIBS -l$lib"; break],
+                [test "$lib" = curses && AC_MSG_ERROR([No terminal library found])])
  done
 ])
 #