Fix location of libtpool.so.2 after 5c1ba994a8b

Commit 5c1ba994a8b inadvertently moved the installed location of a
shared library. Move it back.

Reported by: olivier
Tested by: olivier
Fixes: 5c1ba994a8bcb6676ea3d1bb21b072b90e2d3ae9
Sponsored by: ConnectWise