oprofile, x86: Adding backtrace dump for 32bit process in compat mode

This patch implements the oprofile backtrace  generation for 32 bit
applications running in the 64bit environment (compat mode).

With this change it's possible to get backtrace for 32bits applications
under the 64bits environment using oprofile's callgraph options.

opcontrol --setup -c ...
opreport -l -cg ...

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>