perf-urgent-2020-02-09

 - Kernel fixes:

   - Install cgroup events to the correct CPU context to prevent a
     potential list double add

   - Prevent am intgeer underflow in the perf mlock acounting

   - Add a missing prototyp for arch_perf_update_userpage()

 - Tooling:

   - Add a missing unlock in the error path of maps__insert() in perf maps.

   - Fix the build with the latest libbfd

   - Fix the perf parser so it does not delete parse event terms, which
     caused a regression for using perf with the ARM CoreSight as the sink
     confuguration was missing due to the deletion.

   - Fix the double free in the perf CPU map merging test case

   - Add the missing ustring support for the perf probe command