devel/sobjectizer: update the port to the latest version 5.8.5

• Replace hand-rolled `do-test' target with USES+=cmake:testing
• Do not build tests during the main build stage, this reduces target count from 914 down to 55 and, in turn, the build time which is significant for a C++ project
• Drop the static library, nothing in the ports tree uses it

PR: 293373
Submitted by: diizzy