Objecter::recalc_op_target: fix uninitialized scalar variable

CID 1160848 (#1 of 1): Uninitialized scalar variable (UNINIT)
 uninit_use: Using uninitialized value "best".

Init 'best' with -1 (from the code logic it will be set at least to 0)
to silence coverity.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>