fix openssl library install directory

Summary

In some builds, the Superbuild ssl libray is installed in prefix/lib64 instead of prefix/lib`, causing a compilation error when building CURL in the Superbuild

closes #2058 (closed)

Note that the libdir openssl configuration is the libray path relative to the prefix, not the absolute path.

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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