Configure should sort inc_version_list

Configure should sort inc_version_list

In searching for previous versions of perl, Configure
forgets to sort the directories according to version number,
so 5.10 sorts later than 5.8.

Specifically, without this patch, you'd get something like:

    inc_version_list='5.8.9 5.8.8 5.10.0/i686-linux 5.10.0'

i.e. 5.10.0 would be searched *after* 5.8.8.

With this patch, you get something like:

    inc_version_list='5.10.0/i686-linux 5.10.0 5.8.9 5.8.8'