ncurses: add xterm-256color to terminfo-base

:Release Notes:
This is to address the buildtools-tarball still having problems with certain
xterms.

:Detailed Notes:
Backport from oe-core/master
http://git.openembedded.org/openembedded-core/commit/?id=b367466287e6b1793c38afce6a9524130c48cf86

:Testing Performed:
Only build tested.

:QA Notes:

:Issues Addressed:
[GF-8114] terminfo is missing xterm-256color

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>

Change-Id: Iaf9888d78281108f0bb89f3874f26e031ab4790a
Reviewed-on: https://g2g.palm.com/3257
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>