Fix a warning about an integer change of sign with ICC

The ttl argument to ServiceGaterer::txtFieldReply is uint32_t.

Change-Id: I7df624eb04d5ffea1b281ed06d38d5e66b7a7319
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@nokia.com>

src/libs/zeroconf/avahiLib.cpp

@@ -405,7 +405,7 @@ extern "C" void cAvahiResolveReply(
             sg->txtFieldReply(
                         kDNSServiceFlagsAdd | ((txtAtt->next || address)?kDNSServiceFlagsMoreComing:0),
                         kDNSServiceErr_NoError, static_cast<unsigned short>(txtAtt->size),
-                        txtAtt->text, -1);
+                        txtAtt->text, ~0);
             txtAtt = txtAtt->next;
         }
         if (address){