[Bug go/66303] runtime.Caller() returns infinitely deep stack frames on s390x

[ian at airs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66303

--- Comment #8 from Ian Lance Taylor <ian at airs dot com> ---
The initial stack frame of a goroutine is set up by the makecontext function,
which is part of the C library.  Ideally makecontext should arrange matters
such that a backtrace stops at that point, as pthread_create does.