node_memory: Define the APIs to get/set memory parameters

* include/libvirt/libvirt.h.in: (Add macros for the param fields,
  declare the APIs).
* src/driver.h: (New methods for the driver struct)
* src/libvirt.c: (Implement the public APIs)
* src/libvirt_public.syms: (Export the public symbols)

generator.py

@@ -427,6 +427,8 @@ skip_impl = (
     'virDomainGetDiskErrors',
     'virConnectUnregisterCloseCallback',
     'virConnectRegisterCloseCallback',
+    'virNodeGetMemoryParameters',
+    'virNodeSetMemoryParameters',
 )
 
 qemu_skip_impl = (