LTS couple perf test and perf top fixes

Hi Greg, Sasha,

Can you pick this to 5.4:

commit dbd660e6b2884b864d2642d930a163d3bcebe4be Author: Tommi Rantala tommi.t.rantala@nokia.com Date: Thu Apr 23 14:53:40 2020 +0300

perf test session topology: Fix data path

And this to 5.4 and older LTS trees too:

commit 29b4f5f188571c112713c35cc87eefb46efee612 Author: Tommi Rantala tommi.t.rantala@nokia.com Date: Thu Mar 5 10:37:12 2020 +0200

perf top: Fix stdio interface input handling with glibc 2.28+

Thanks! -Tommi