runtime: remove systemstack logic from adjustframe
Remove logic for skipping some adjustframe logic for systemstack (aka
FuncID_systemstack_switch). This was introduced in 2014 by
9198ed4bd6ec7b7dd37aa2797e96f15ddbb1e6cd but doesn't seem to be needed
anymore.
Updates #59692
Change-Id: I2368d64f9bb28ced4e7f15c9b15dac7a29194389
Reviewed-on: https://go-review.googlesource.com/c/go/+/489116
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>