rpm: force removal os-prober package

It can be can be harmful, because it accesses (and mounts) every block
device, including VM controlled /dev/loop*.

rpm_spec/core-dom0-linux.spec

@@ -49,6 +49,11 @@ Requires:	qubes-core-dom0
 Requires:	qubes-utils >= 2.0.6
 Requires:	%{name}-kernel-install
 
+# get rid of os-prober, it tries to mount and parse all the block devices in
+# the system, including loop*
+Provides: os-prober
+Obsoletes: os-prober
+
 %define _builddir %(pwd)
 
 %description