Newer boost is more picky with null pointers

Change-Id: I7a2bcd802ad9316696398a2e176dc03ea25baed1

vcl/quartz/salbmp.cxx

@@ -280,7 +280,7 @@ bool QuartzSalBitmap::AllocateUserData()
     catch( const std::bad_alloc& )
     {
         OSL_FAIL( "vcl::QuartzSalBitmap::AllocateUserData: bad alloc" );
-        maUserBuffer.reset( NULL );
+        maUserBuffer.reset( static_cast<sal_uInt8*>(NULL) );
         mnBytesPerRow = 0;
     }