qapi: introduce "size" type

v1->v2:
- fall back to uint64 rather than int

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 1292476..8082af3 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -163,6 +163,8 @@
           name == 'int64' or name == 'uint8' or name == 'uint16' or
           name == 'uint32' or name == 'uint64'):
         return name + '_t'
+    elif name == 'size':
+        return 'uint64_t'
     elif name == 'bool':
         return 'bool'
     elif name == 'number':