rtld: fix display of the mapbase for the traced objects

rtld: fix display of the mapbase for the traced objects

Commit 24d0c9c1f565bab6e introduced the following regression:
% ldd /bin/ls
/bin/ls:
        libutil.so.9 => /lib/libutil.so.9 (0x1021000)
        libncursesw.so.9 => /lib/libncursesw.so.9 (0x1021000)
        libc.so.7 => /lib/libc.so.7 (0x1021000)
Note that the base address is the same for all displayed libraries.

Fix it by passing correct object to trace_print_obj().

Fixes:	24d0c9c1f565bab6e
Reviewed by:	jrtc27
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Differential revision:	https://reviews.freebsd.org/D36198