rsyslog: remove the dependency on valgrind for mips64n32

valgrind is not supported mips64n32, so remove it

Signed-off-by: Yue Tao <Yue.Tao@windriver.com>
Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>