Add most relevant vg_attr fields as lvm2app 'get' functions.

Of the vgs field vg_attr, a few of the most likely to be used attributes
are clustered, exported, and partial.  This patch adds the following 3
functions:
uint64_t lvm_vg_is_clustered(const vg_t vg)
uint64_t lvm_vg_is_exported(const vg_t vg)
uint64_t lvm_vg_is_partial(const vg_t vg)

lib/metadata/metadata-exported.h

@@ -721,6 +721,7 @@ uint64_t vg_max_pv(const struct volume_group *vg);
 uint64_t vg_max_lv(const struct volume_group *vg);
 int vg_check_write_mode(struct volume_group *vg);
 #define vg_is_clustered(vg) (vg_status((vg)) & CLUSTERED)
+#define vg_is_exported(vg) (vg_status((vg)) & EXPORTED_VG)
 
 struct vgcreate_params {
 	char *vg_name;

liblvm/lvm2app.h

@@ -480,6 +480,43 @@ int lvm_vg_reduce(vg_t vg, const char *device);
  */
 int lvm_vg_set_extent_size(vg_t vg, uint32_t new_size);
 
+/**
+ * Get whether or not a volume group is clustered.
+ *
+ * \param   vg
+ * VG handle obtained from lvm_vg_create or lvm_vg_open.
+ *
+ * \return
+ * 1 if the VG is clustered, 0 if not
+ */
+uint64_t lvm_vg_is_clustered(vg_t vg);
+
+/**
+ * Get whether or not a volume group is exported.
+ *
+ * \param   vg
+ * VG handle obtained from lvm_vg_create or lvm_vg_open.
+ *
+ * \return
+ * 1 if the VG is exported, 0 if not
+ */
+uint64_t lvm_vg_is_exported(vg_t vg);
+
+/**
+ * Get whether or not a volume group is a partial volume group.
+ *
+ * When one or more physical volumes belonging to the volume group
+ * are missing from the system the volume group is a partial volume
+ * group.
+ *
+ * \param   vg
+ * VG handle obtained from lvm_vg_create or lvm_vg_open.
+ *
+ * \return
+ * 1 if the VG is PVs, 0 if not
+ */
+uint64_t lvm_vg_is_partial(vg_t vg);
+
 /**
  * Get the current metadata sequence number of a volume group.
  *

liblvm/lvm_vg.c

@@ -243,6 +243,21 @@ uint64_t lvm_vg_get_seqno(const vg_t vg)
 	return vg_seqno(vg);
 }
 
+uint64_t lvm_vg_is_clustered(const vg_t vg)
+{
+	return vg_is_clustered(vg);
+}
+
+uint64_t lvm_vg_is_exported(const vg_t vg)
+{
+	return vg_is_exported(vg);
+}
+
+uint64_t lvm_vg_is_partial(const vg_t vg)
+{
+	return (vg_missing_pv_count(vg) != 0);
+}
+
 /* FIXME: invalid handle? return INTMAX? */
 uint64_t lvm_vg_get_size(const vg_t vg)
 {