Remove %clean section

None of currently supported distributions need that.
Last one was EL5 which is EOL for a while.

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

arj.spec

@@ -83,9 +83,6 @@ install -p -m 644 %{SOURCE2} $RPM_BUILD_ROOT%{_mandir}/man1/unarj.1
 rm -f $RPM_BUILD_ROOT%{_bindir}/arj-register
 rm -f $RPM_BUILD_ROOT%{_mandir}/man1/arj-register.1*
 
-%clean
-rm -rf $RPM_BUILD_ROOT
-
 %files
 %defattr(-,root,root,-)
 %{!?_licensedir:%global license %%doc}