tests: Remove unused variable.
tests: Remove unused variable.

And include missing assertion.

Addressing:
test_probes_sysinfo.c: In function ‘main’:
test_probes_sysinfo.c:15:7: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]

postfix/openscap,jan-cerny/openscap,openprivacy/openscap,OpenSCAP/openscap,ybznek/openscap,openprivacy/openscap,redhatrises/openscap,isimluk/openscap,Hexadorsimal/openscap,mpreisler/openscap,Hexadorsimal/openscap,OpenSCAP/openscap,jan-cerny/openscap,redhatrises/openscap,redhatrises/openscap,mpreisler/openscap,isimluk/openscap,openprivacy/openscap,isimluk/openscap,Hexadorsimal/openscap,jan-cerny/openscap,ybznek/openscap,jan-cerny/openscap,postfix/openscap,redhatrises/openscap,redhatrises/openscap,OpenSCAP/openscap,OpenSCAP/openscap,OpenSCAP/openscap,openprivacy/openscap,postfix/openscap,jan-cerny/openscap,mpreisler/openscap,Hexadorsimal/openscap,postfix/openscap,ybznek/openscap,ybznek/openscap,jan-cerny/openscap,ybznek/openscap,mpreisler/openscap,OpenSCAP/openscap,mpreisler/openscap,openprivacy/openscap,Hexadorsimal/openscap,isimluk/openscap,isimluk/openscap,postfix/openscap,openprivacy/openscap,ybznek/openscap,postfix/openscap,mpreisler/openscap,Hexadorsimal/openscap,isimluk/openscap,redhatrises/openscap