Fix for bug 34510 - Minidump target does not resolve new symbols correctly
Even though the content of the minidump does not change in a debugging session,
frames can't be indiscriminately be cached since modules and symbols can be
explicitly added after the minidump is loaded.
The fix is simple, just let the base Thread::ClearStackFrames() do its job.
submitted by amccarth on behalf of lemo
Differential Revision: https://reviews.llvm.org/D37527