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>

libyubikey.spec

@@ -39,9 +39,6 @@ export LD_LIBRARY_PATH=${RPM_BUILD_DIR}/%{name}-%{version}/.libs
 %{__rm} -rf $RPM_BUILD_ROOT
 %{__make} install DESTDIR=$RPM_BUILD_ROOT INSTALL="%{__install} -p"
 
-%clean
-%{__rm} -rf $RPM_BUILD_ROOT
-
 %post -p /sbin/ldconfig
 
 %postun -p /sbin/ldconfig