Patch by Herbert Xu <herbert@gondor.apana.org.au>:

As of 2.5.74, make oldconfig always disables existing optional choices
even if they were selected previously.  For example, if all the EICON
ISDN drivers were selected as modules, then make oldconfig will turn
them off.

Part of the problem is that the choice value itself is computed before
the SYMBOL_NEW flag is turned off.  This patch addresses that particular
problem.