* tracepoint.c (tfile_xfer_partial): If there's no traceframe
selected, don't try iterating over the traceframe's blocks.
(tfile_has_stack): If there's no traceframe selected, then there's
no stack.
(tfile_has_registers): If there's no traceframe selected, then
there's no registers.
gdb/testsuite/
* gdb.trace/tfile.exp: Test that with no traceframe selected,
there's no stack or registers.
ffd5ec2486