xbmc.sh: read Release info from os-release
If /etc/os-release exists, read the info from there
instead of relying on lsb_release.

see also commit 7a9aa6f5d9ac8df1c79eb06ed63bce8af162c3ba
xbmc.sh: extract core dump from systemd's journal
On systemd systems, core dumps are - by default - written to systemd's
logging system, the journal. The print_crash_report function only
searches certain directories for the core dump, but would never find
it in the journal, resulting in an empty stack trace in the crash log.
As a workaround, simply extract the last core dump caused by xbmc.bin
to "core" where the single_stacktrace function will find it.
If the system is configured to not dump cores into the journal,
systemd-coredumpctl will simply fail silently.

see also http://www.freedesktop.org/software/systemd/man/systemd-coredumpctl.html
Merge pull request #3086 from mus65/xbmc.sh

[Linux] small xbmc.sh crashlog improvements