[RT:PATCH] tracing/x86: Add check to GCC messing with mcountprologue

[John Kacur]

This patch is originally from Steven Rostedt.
I cherry-picked it from his git repo, and ported it to v2.6.33.2-rt13
by fixing up the merge conflicts.

The immediate importance of this, is that it restores the function_graph 
tracer to 32-bit x86, for real-time.

I have done some light testing on 32-bit x86, but it could use some more
testing everywhere. After that I hope that Thomas will pick it up for the
next 2.6.33.2-rtN release.

I have done this for real-time purposes, but Steven's patch was intended
for the mainline kernel, so maybe some testing in -rt would convince
folks to pick it up for mainline as well, if it isn't already queued up.

John Kacur