Add stacktrace support, which is required for lockdep and tracing.  The
stack tracing simply looks at all kernel text symbols found on the
stack, similar to the trap stack dumping code, which can also be
converted to use this.
Signed-off-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NJesper Nilsson <jesper.nilsson@axis.com>