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>

rubberband.spec

@@ -46,9 +46,6 @@ make install DESTDIR=$RPM_BUILD_ROOT
 find $RPM_BUILD_ROOT -name '*.la' -exec rm -f {} ';'
 rm -rf $RPM_BUILD_ROOT%{_libdir}/*.a
 
-%clean
-rm -rf $RPM_BUILD_ROOT
-
 
 %post -p /sbin/ldconfig