vbox: Rewrite vboxDomainSnapshotCreateXML

The vboxDomainSnapshotCreateXML integrated the snapshot redefine
with this patch:
http://www.redhat.com/archives/libvir-list/2014-May/msg00589.html
This patch introduced vboxSnapshotRedefine in vboxUniformedAPI to
enable the features.

This patch replace all version specified APIs to the uniformed api,
then, moving the whole implementation to vbox_common.c. As there
is only API level changes, the behavior of the function doesn't
change.

Some old version's defects has brought to the new one. The already
known things are:
    *goto cleanup in a loop without releasing the pointers in the
    loop.
    *When function failed after machine unregister, no roll back
    to recovery it and the virtual machine would disappear.

src/vbox/vbox_common.h

@@ -247,6 +247,24 @@ enum MediumType
     MediumType_Writethrough = 2,
 };
 
+enum CleanupMode
+{
+    CleanupMode_UnregisterOnly = 1,
+    CleanupMode_DetachAllReturnNone = 2,
+    CleanupMode_DetachAllReturnHardDisksOnly = 3,
+    CleanupMode_Full = 4
+};
+
+enum MediumVariant
+{
+    MediumVariant_Standard = 0,
+    MediumVariant_VmdkSplit2G = 0x01,
+    MediumVariant_VmdkStreamOptimized = 0x04,
+    MediumVariant_VmdkESX = 0x08,
+    MediumVariant_Fixed = 0x10000,
+    MediumVariant_Diff = 0x20000
+};
+
 /* Simplied definitions in vbox_CAPI_*.h */
 
 typedef void const *PCVBOXXPCOM;

src/vbox/vbox_uniformed_api.h

@@ -552,6 +552,11 @@ int vboxDomainUpdateDeviceFlags(virDomainPtr dom, const char *xml,
 int vboxDomainDetachDevice(virDomainPtr dom, const char *xml);
 int vboxDomainDetachDeviceFlags(virDomainPtr dom, const char *xml,
                                 unsigned int flags);
+virDomainSnapshotPtr
+vboxDomainSnapshotCreateXML(virDomainPtr dom,
+                            const char *xmlDesc,
+                            unsigned int flags);
+
 
 /* Version specified functions for installing uniformed API */
 void vbox22InstallUniformedAPI(vboxUniformedAPI *pVBoxAPI);