Bug#1059856: correction to patch

[Nicola Manini]

Hello,
                it seems that the folder /etc/environment.d is not honored.
So my suggested patch (involving adding a file there) fails.
A workaround is to add the following line:
MOZ_USE_XINPUT2=1
to configuration file
/etc/environment

This method does work.
But I ignore if modifying a configuration file is consistent with Debian 
packaging policies.

Thanx! Best,
                        NM