Downgrade the "direct comparison" error for ObjC literals to a warning.

Chris pointed out that while the comparison is certainly problematic
and does not have well-defined behavior, it isn't any worse than some
of the other abuses that we merely warn about and doesn't need to make
the compilation fail.

Revert the release notes change (r159766) now that this is just a new warning.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159939 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html
index 6c38c71..b820e8d 100644
--- a/docs/ReleaseNotes.html
+++ b/docs/ReleaseNotes.html
@@ -218,21 +218,7 @@
 <h3 id="objcchanges">Objective-C Language Changes in Clang</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 
-<ul>
-  <li>
-    <p>It is now an error to compare against the addresses of Objective-C
-       literals. This is usually a simple mistake (using <code>==</code> instead
-       of <code>-isEqual:</code>), and the result depends on the implementation
-       of the various literals, none of which are guaranteed to be uniqued or
-       always newly-allocated.</p>
-    <p>In the past, we allowed comparisons against literal strings
-       (<code>@"..."</code>), since they are currently uniqued across
-       translation units at link time. This is an implementation detail and
-       should not be relied upon. If you are using such code, please use global
-       string constants instead (<code>NSString * const MyConst = @"..."</code>)
-       or use <code>-isEqual:</code>.</p>
-  </li>
-</ul>
+<p>...</p>
 
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="apichanges">Internal API Changes</h3>