extensive orb_advert_t fixes

The calls to orb_advertise were being mishandled throughout the code.
There were ::close() calls on memory pointers, there were checks
against < 0 when it is a pointer to a object and values larger than
0x7ffffffff are valid. Some places orb_advert_t variables were
being initialized as 0 other places as -1.

The orb_advert_t type was changed to uintptr_t so the pointer value
would not be wrapped as a negative number. This was causing a failure
on ARM.

Tests for < 0 were changed to == 0 since a null pointer is the valid
representation for error, or uninitialized.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/modules/uORB/uORBManager_nuttx.cpp

@@ -89,18 +89,18 @@ orb_advert_t uORB::Manager::orb_advertise_multi(const struct orb_metadata *meta,
   /* open the node as an advertiser */
   fd = node_open(PUBSUB, meta, data, true, instance, priority);
   if (fd == ERROR)
-    return ERROR;
+    return 0;
 
   /* get the advertiser handle and close the node */
   result = ioctl(fd, ORBIOCGADVERTISER, (unsigned long)&advertiser);
   close(fd);
   if (result == ERROR)
-    return ERROR;
+    return 0;
 
   /* the advertiser must perform an initial publish to initialise the object */
   result = orb_publish(meta, advertiser, data);
   if (result == ERROR)
-    return ERROR;
+    return 0;
 
   return advertiser;
 }