rados_sync.cc: fix xattr_diff() for the only_in_b checks

In the checks to build only_in_b up the wrong const_iterator x is
build up. it should compare rhs->xattrs with xattrs entries and
not twice rhs->xattrs.

Fix for:

CID 716957 (#1 of 1): Invalid iterator comparison (MISMATCHED_ITERATOR)
 mismatched_comparison: Comparing x from rhs->xattrs to this->xattrs.end()
 from this->xattrs.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>

Author: dalgaaf

src/tools/rados/rados_sync.cc

@@ -504,6 +504,7 @@ void BackedUpObject::xattr_diff(const BackedUpObject *rhs,
   only_in_a.clear();
   only_in_b.clear();
   diff.clear();
+
   for (std::map < std::string, Xattr* >::const_iterator x = xattrs.begin();
 	 x != xattrs.end(); ++x)
   {
@@ -518,10 +519,11 @@ void BackedUpObject::xattr_diff(const BackedUpObject *rhs,
 	diff.push_back(x->first);
     }
   }
+
   for (std::map < std::string, Xattr* >::const_iterator r = rhs->xattrs.begin();
 	 r != rhs->xattrs.end(); ++r)
   {
-    std::map < std::string, Xattr* >::const_iterator x = rhs->xattrs.find(r->first);
+    std::map < std::string, Xattr* >::const_iterator x = xattrs.find(r->first);
     if (x == xattrs.end()) {
       only_in_b.push_back(r->first);
     }