spec cleanup: get rid of redundant defattr

References (first one is a direct trigger):
https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/KEO7AX3JXR2TY6OVL4M7HDISZ6YIJNKU/#2UFET77NHMJTG4NA2ECRVH2KO3W56ZWD
http://rpm.org/gitweb?p=rpm.git;a=commit;h=47ea5da (~2004)