mgr/BaseMgrModule: use PyInt_Check() to compatible with py2

mgr/BaseMgrModule: use PyInt_Check() to compatible with py2

in python2, we have both `PyLongObject` and `PyIntObject` for presenting
`long` and `int` types. and in python3, `PyIntObject` is dropped, `int`
is represented using `PyLongObject`. and the related functions like
`PyInt_Check()` and `PyInt_AsLong()` are removed along with
`PyIntObject`.

so we should use different set of functions for converting an `int` python
object to native type in C++. since we don't use `long` for "count" when
calling `MgrModule.set_health_checks()`, in this change, we just define
a macro to unify the difference between python2 and python3.

the same applies to "max_count" parameter of `MgrModule.add_osd_perf_query()`
call.

Signed-off-by: Kefu Chai <kchai@redhat.com>