Description: perf: Tighten (and fix) the grouping condition
References:
 https://source.android.com/security/bulletin/2017-05-01
Notes:
 carnil> According to upstream commit it should fix
 carnil> 9fc81d87420d ("perf: Fix events installation
 carnil> during moving group"), which is in 3.19-rc1.
 carnil> so might actually be not affecting any other
 carnil> release, but needs check
 nsl> 9fc81d87420d was backported to 3.16 in 3.16.35
 nsl> along with the fix. 3.16 was likely never 
 nsl> vulnerable, but nonetheless has the fix.
 carnil> 9fc81d87420d backported to 3.16.7-ckt4
 carnil> c3c87e770458 backported to 3.16.7-ckt6
 carnil> the fix for 3.16 is as well in 3.16.35 thus
 canril> no release in 3.16-upstream-stable contained
 carnil> the vulnerability.
 carnil> So the issue was introduced and fixed in two
 carnil> different releases still while beeing maintained
 carnil> by the Ubuntu Kernel team and before "upstreamed"
 carnil> back.
Bugs:
upstream: released (3.19-rc7) [c3c87e770458aa004bd7ed3f29945ff436fd6511]
4.9-upstream-stable: N/A "Fixed before branching point"
3.16-upstream-stable: released (3.16.35) [08446eea4a583919b979915f4dec2fa94ac6186c]
3.2-upstream-stable: N/A "Vulnerable code not present"
sid: released (3.16.7-ckt7-1)
3.16-jessie-security: N/A "Fixed before branching point for jessie"
3.2-wheezy-security: N/A "Vulnerable code not present"