qapi: merge QInt and QFloat in QNum

We would like to use a same QObject type to represent numbers, whether
they are int, uint, or floats. Getters will allow some compatibility
between the various types if the number fits other representations.

Add a few more tests while at it.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170607163635.17635-7-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[parse_stats_intervals() simplified a bit, comment in
test_visitor_in_int_overflow() tidied up, suppress bogus warnings]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/blockdev.c b/blockdev.c
index 6472548..18acc5b 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -334,8 +334,9 @@
             break;
         }
 
-        case QTYPE_QINT: {
-            int64_t length = qint_get_int(qobject_to_qint(entry->value));
+        case QTYPE_QNUM: {
+            int64_t length = qnum_get_int(qobject_to_qnum(entry->value));
+
             if (length > 0 && length <= UINT_MAX) {
                 block_acct_add_interval(stats, (unsigned) length);
             } else {