ISA_cfa_plugin.py: improve error reporting
ISA_cfa_plugin.py: improve error reporting

When process_file() raises an exception,
python2.7/multiprocessing/pool.py re-raises that exception in the main
process with a different backtrace, which makes it hard to trace down
where the error really occurred.

The wrapper function now prints that location before returning to the
calling process.

Signed-off-by: Patrick Ohly <0fc9d825c622b2a5ac5160289c29f03654b10648@intel.com>

01org/meta-security-isafw