util: bitmap: use VIR_AUTOPTR for aggregate types

By making use of GNU C's cleanup attribute handled by the
VIR_AUTOPTR macro for declaring aggregate pointer variables,
majority of the calls to *Free functions can be dropped, which
in turn leads to getting rid of most of our cleanup sections.

Signed-off-by: Sukrit Bhatnagar <skrtbhtngr@gmail.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>

src/util/virbitmap.c

@@ -1202,15 +1202,12 @@ char *
 virBitmapDataFormat(const void *data,
                     int len)
 {
-    virBitmapPtr map = NULL;
-    char *ret = NULL;
+    VIR_AUTOPTR(virBitmap) map = NULL;
 
     if (!(map = virBitmapNewData(data, len)))
         return NULL;
 
-    ret = virBitmapFormat(map);
-    virBitmapFree(map);
-    return ret;
+    return virBitmapFormat(map);
 }