Removes tautological null checks in mongodb.

tautological_null.patch

diff --git a/src/mongo/client/dbclientcursor.h b/src/mongo/client/dbclientcursor.h
index 785734d..11b6349 100644
--- a/src/mongo/client/dbclientcursor.h
+++ b/src/mongo/client/dbclientcursor.h
@@ -116,7 +116,7 @@ namespace mongo {
            'dead' may be preset yet some data still queued and locally
            available from the dbclientcursor.
         */
-        bool isDead() const { return  !this || cursorId == 0; }
+        bool isDead() const { return cursorId == 0; }

         bool tailable() const { return (opts & QueryOption_CursorTailable) != 0; }

diff --git a/src/mongo/client/dbclientcursor.cpp b/src/mongo/client/dbclientcursor.cpp
index f6dc575..468ed78 100644
--- a/src/mongo/client/dbclientcursor.cpp
+++ b/src/mongo/client/dbclientcursor.cpp
@@ -308,9 +308,6 @@ namespace mongo {
     }

     DBClientCursor::~DBClientCursor() {
-        if (!this)
-            return;
-
         DESTRUCTOR_GUARD (

         if ( cursorId && _ownCursor && ! inShutdown() ) {
diff --git a/src/mongo/util/concurrency/mutexdebugger.h b/src/mongo/util/concurrency/mutexdebugger.h.bak
index f0674e6..ff652ff 100644
--- a/src/mongo/util/concurrency/mutexdebugger.h
+++ b/src/mongo/util/concurrency/mutexdebugger.h.bak
@@ -87,7 +87,7 @@ namespace mongo {
         }

         void entering(mid m) {
-            if( this == 0 || m == 0 ) return;
+            if( m == 0 ) return;
             verify( magic == 0x12345678 );

             Preceeding *_preceeding = us.get();
@@ -147,7 +147,7 @@ namespace mongo {
             }
         }
         void leaving(mid m) {
-            if( this == 0 || m == 0 ) return; // still in startup pre-main()
+            if( m == 0 ) return; // still in startup pre-main()
             Preceeding& preceeding = *us.get();
             preceeding[m]--;
             if( preceeding[m] < 0 ) {