fixed detection of ncurses dependency

Signed-off-by: Joerg Seitter <adk@seitter.net>

package/net-snmp/patches/patch-configure_d_config_os_libs2

@@ -0,0 +1,12 @@
+--- net-snmp-5.8.orig/configure.d/config_os_libs2	2018-07-16 16:33:40.000000000 +0200
++++ net-snmp-5.8/configure.d/config_os_libs2	2019-10-06 12:45:37.396843992 +0200
+@@ -604,6 +604,9 @@ AC_CHECK_FUNCS(nlist nlist64 knlist)
+ AC_CHECK_HEADERS([curses.h])
+ AC_CHECK_HEADERS([ncurses/curses.h])
+ NETSNMP_SEARCH_LIBS([endwin], [curses ncurses],,,,[LIBCURSES])
++if test -n "$LIBCURSES"; then
++  NETSNMP_SEARCH_LIBS([halfdelay], [tinfo], [LIBCURSES="$LIBCURSES $LIBTINFO"],,,[LIBTINFO])
++fi
+ AC_SUBST([LIBCURSES])
+ 
+ #   libm for ceil