Patch from Tim Rowley <tor@cs.brown.edu>.

From his email:

Your checkin v1.9 to nsDirectoryService.cpp broke a SUNWspro4.2
debug build of mozilla, causing xpcom to fail initializing.  The
root problem was that nsDirectoryService::Create() was failing.
This appears to a mistake caused by a shadowed copy of the "rv"
variable in that method.  The fix below causes the SUNWspro build
to start up normally.

Not sure why this didn't break other platforms.

xpcom/io/nsDirectoryService.cpp

@@ -299,7 +299,7 @@ nsDirectoryService::Create(nsISupports *outer, REFNSIID aIID, void **aResult)
         // use this to temporarily hold a reference to mService:
         nsCOMPtr<nsIDirectoryService> serv = mService;
 
-        nsresult rv = mService->Init();
+        rv = mService->Init();
         if (NS_FAILED(rv)) return rv;
         rv = mService->QueryInterface(aIID, aResult);
     }