uim: use _remove operator to drop silent rules

When MACHINE=qemux86-64 and enable multilib, lib32-uim fails to build
because CONFIGUREOPTS isn't expanded correctly.

See similar issue:
http://lists.openembedded.org/pipermail/openembedded-core/2013-November/086510.html



Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>