Report the perl executable path in the error if Config.pm is out of sync.

Report the perl executable path in the error if Config.pm is out of sync.

If the version that Config.pm was built for differs from the version of the
perl executable running it, Config.pm aborts with an error message. The
error message was updated to include $0 (the script filename) in Aug 2010 by
commit b982c5de5a0d9f6f. Somewhat misleadingly the commit message says
"include the path of the perl executable in the error message." which $0 is
not.

This commit adds $^X to the error message - the path of the perl executable.
The error message also shows the script name, as this might also be useful
in diagnosing the cause of the problem.