Description of problem:
Cannot use setIOThreadParams() to set poll_shrink.

Version-Release number of selected component (if applicable):
python3-libvirt-5.0.0-2.module+el8+2780+89be6baf.x86_64
libvirt-5.0.0-3.module+el8+2807+8bbe0a41.x86_64

How reproducible
100%

Steps to Reproduce:
# python
Python 3.6.8 (default, Jan 11 2019, 02:17:16)
[GCC 8.2.1 20180905 (Red Hat 8.2.1-3)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import libvirt
>>> conn = libvirt.open()
>>> dom = conn.lookupByName('test')
>>> dom.addIOThread(200, 0)
0
>>> dom_stats = conn.domainListGetStats([dom], libvirt.VIR_DOMAIN_STATS_IOTHREAD, 0)
>>> dom_stats
[(<libvirt.virDomain object at 0x7f9dd15bb550>, {'iothread.count': 1, 'iothread.200.poll-max-ns': 32768, 'iothread.200.poll-grow': 0, 'iothread.200.poll-shrink': 0})]
>>> dom.setIOThreadParams(200, {'poll_shrink': 6}, 0)
libvirt:  error : invalid argument: invalid type 'ullong' for parameter 'poll_shrink', expected 'uint'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 2250, in setIOThreadParams
    if ret == -1: raise libvirtError ('virDomainSetIOThreadParams() failed', dom=self)
libvirt.libvirtError: invalid argument: invalid type 'ullong' for parameter 'poll_shrink', expected 'uint'
>>>

Actual results:
Set failed.

Expected results:
Set poll_shrink successful.

Additional info:
The type of poll_shrink in libvirt-python is different in libvirt.

Line 1687 in libvirt-python-5.0.0-2/libvirt-override.c.
static virPyTypedParamsHint virPyDomainSetIOThreadParams[] = {
    { VIR_DOMAIN_IOTHREAD_POLL_MAX_NS, VIR_TYPED_PARAM_ULLONG },
    { VIR_DOMAIN_IOTHREAD_POLL_GROW, VIR_TYPED_PARAM_UINT },
    { VIR_DOMAIN_IOTHREAD_POLL_SHRINK, VIR_TYPED_PARAM_ULLONG },
};



Line 6156 in libvirt/src/qemu/qemu_driver.c.
6144qemuDomainIOThreadParseParams(virTypedParameterPtr params,
6145                              int nparams,
6146                              qemuMonitorIOThreadInfoPtr iothread)
...
6150    if (virTypedParamsValidate(params, nparams,
6151                               VIR_DOMAIN_IOTHREAD_POLL_MAX_NS,
6152                               VIR_TYPED_PARAM_ULLONG,
6153                               VIR_DOMAIN_IOTHREAD_POLL_GROW,
6154                               VIR_TYPED_PARAM_UINT,
6155                               VIR_DOMAIN_IOTHREAD_POLL_SHRINK,
6156                               VIR_TYPED_PARAM_UINT,
6157                               NULL) < 0)