Remove shadowing variable from traverse_trees()

Remove shadowing variable from traverse_trees()

The variable named entry is allocated using malloc() and then
forgotten, it being shadowed by an automatic variable of the
same name.  Fixing the array size at 3 worked so far because
the only caller of traverse_trees() needed only as much
entries.  Simply remove the shadowing varaible and we're able
to traverse more than three trees and save stack space at the
same time!

Signed-off-by: Rene Scharfe <redacted>
Signed-off-by: Junio C Hamano <redacted>