libre: qtcreator: remove unused libre.patch
The usage of the libre.patch has already been removed by the following
commit:
e0a236ce2aaf35673906212a7bcc3ab09ec71de6
(libre: qtcreator: sync from core from 4.12.4-1 to 4.14.0-4)
but in that commit I forgot to also remove the actual libre.patch file.
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>