Fix comparisons between signed & unsigned integers

When python3 builds C modules, it adds the -Wsign-compare flag to GCC.
This creates lots of warnings where we compare a 'size_t' value against
an 'int' value due to signed/unsigned difference.  Change all the size_t
types to ssize_t to address this.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

typewrappers.c

@@ -319,7 +319,7 @@ libvirt_ulonglongUnwrap(PyObject *obj,
         PyErr_SetString(PyExc_TypeError, "an integer is required");
     }
 
-    if ((ullong_val == -1) && PyErr_Occurred())
+    if ((ullong_val == (unsigned long long)-1) && PyErr_Occurred())
         return -1;
 
     *val = ullong_val;