remove limitation to only be able to report if the running kernel is no mainline kernel

[Karl-Philipp Richter]

Whilst it's necessary to enforce mainline kernel bugs to be directed upstream immediately it's not constructive to prevent reporting issues of an Ubuntu kernel if a mainline kernel is running, e.g. if the Ubuntu kernel 4.4.0-9-generic of 16.04 doesn't start, but the previously installed 4.2.5 mainline does, then the user might want to invoke `ubuntu-bug linux-image-4.4.0-9-generic` and report against the Ubuntu kernel, but can't because `apport` refuses since a mainline kernel is running.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: apport 2.19.1-0ubuntu5
Uname: Linux 4.4.3-040403-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CrashReports: 600:0:116:629218:2016-02-29 21:56:39.476244786 +0100:2016-02-29 21:56:38.308256442 +0100:/var/crash/dlm.0.crash
CurrentDesktop: Unity
Date: Fri Mar 4 12:56:25 2016
InstallationDate: Installed on 2013-10-17 (868 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
PackageArchitecture: all
SourcePackage: apport
UpgradeStatus: Upgraded to wily on 2015-11-19 (105 days ago)
modified.conffile..etc.default.apport:
 # set this to 0 to disable apport, or to 1 to enable it
 # you can temporarily override this with
 # sudo service apport start force_start=1
 enabled=0
mtime.conffile..etc.default.apport: 2013-10-21T23:07:05.378054

[Brian Murray (brian-murray)]

There may be some concern here about apport gathering information about the kernel not in use. Like maybe /proc/fb is different or something.