Configure: catch the build tree configdata.pm

There are things depending on configdata.pm.  However, it's perfectly
possible that there is one in the source directory from a previous
build, and that might disrupt an out of source build.  To avoid this
conflict, make sure never to use the source tree configdata.pm in that
case, i.e. make the hard assumption that it's a generated file in the
build tree, which it is.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5546)