ObsoleteFiles.inc: Don't try and delete /usr/lib32/libdtrace.so.2

OLD_FILES and OLD_LIBS implicitly include the libcompat variant, whereas
MOVED_LIBS exists specifically for files that have moved between /lib
and /usr/lib, and thus don't get a libcompat equivalent.

Reported by: des
Fixes: 5fd1da4d8501 ("ObsoleteFiles.inc: Add an entry for libdtrace.so.2 in /usr/lib")