config: Don't finalize mount state in selinux_set_policy_root()

This breaks every further call to e.g. `is_selinux_enabled()` after a policy
root has been set.  This tripped up some code landed in libostree:
ostreedev/ostree#797
Since in some cases we initialize a policy twice in process, and we'd
call `is_selinux_enabled()` each time.

More info in: http://marc.info/?l=selinux&m=149323809332417&w=2

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

libselinux/src/selinux_config.c

@@ -282,7 +282,6 @@ int selinux_set_policy_root(const char *path)
 	}
 	policy_type++;
 
-	fini_selinuxmnt();
 	fini_selinux_policyroot();
 
 	selinux_policyroot = strdup(path);