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>

libmodplug.spec

@@ -48,9 +48,6 @@ rm -f $RPM_BUILD_ROOT%{_libdir}/*.la
 make check
 
 
-%clean
-rm -rf $RPM_BUILD_ROOT
-
 
 %post -p /sbin/ldconfig