• Support newer libedit by using different name for a constant (fixes build on current)
• Switch to USES=libedit as suggested by stage-qa:

http://poudriere.amdmi3.ru/data/10-amd64-default/failures_all_2015_09_28/logs/errors/ufmcontrol-i18n-0.3.5.log

• Fix indentation
• Set DATADIR, fixing xufmrc installation. Without that, incorrect DATADIR is created, and xufmrc is installed AS (as opposed to `into') share/ufmcontrol.

PR: 203490
Submitted by: amdmi3