lttng-tools: bump to version 2.7.0
0001-Fix-Mark-MI-and-Config-string-declarations-as-extern.patch
is gone with commit 4965f956f3ef47388fb4a1b2f8f504abfe31afe7.
Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>