Remove: performance measurements in YAPF

YAPF was constantly measuring its performance, but only at
certain debug-levels this information was shown.

Now after years, I sincerely wonder if anyone still knows about this
feature and who still use it. Especially with the new framerate window,
this detailed performance is not as meaningful anymore as it once
was.

(cherry picked from commit 665a3928e2)

src/pathfinder/yapf/yapf_rail.cpp

@@ -66,8 +66,6 @@ template <typename Tpf> void DumpState(Tpf &pf1, Tpf &pf2)
 	fclose(f2);
 }
 
-int _total_pf_time_us = 0;
-
 template <class Types>
 class CYapfReserveTrack
 {