ftrace updates

Due to the new mcount recording method, the assumptions about the records that hold the mcount locations have changed. Now we need to protect reading and writing of the records between module load and reading of the debugfs files. There is not much contention here, but they need to be protected none the less.

I simply use the ftrace_lock to accomplish this. The ftrace_lock should never be held under interrupt context so disabling interrupts should not be necessary. I've run this under lockdep and lockdep has not complained.

-- Steve