tools: rework on vm ops

There are some problems to use VM operations in a deamon process,
such as Acrnd.  the list_vm() does not return VM informations, it
just print VM information to stdio, so we have get_vm_list()
to get VM list head vmngr_head; get_vm_list() always creates a
new fresh vm list every time, and must use put_vm_list() to delete
old list. So Acrnd need to create and destroy vm list frequently.
In fact we just need the vmngr_head to be an extern variable. And
to make it refreshable.We can insert new VMs, remove dead ones,
and update their state.

Reviewed-by: Yan Like <like.yan@intel.com>
Signed-off-by: Tao Yuhong <yuhong.tao@intel.com>

tools/acrn-manager/Makefile

@@ -3,6 +3,7 @@ OUT_DIR ?= .
 
 CFLAGS := -Wall
 CFLAGS += -I../../devicemodel/include
+CFLAGS += -I../../devicemodel/include/public
 ifeq ($(RELEASE),0)
 CFLAGS += -g -DMNGR_DEBUG
 endif