config.log is not in build directory after 8u backport of JDK-8079891

Configure, and see:

jdk8u-dev $ find | grep config.log
config.log

...while it should be here:

jdk8u-dev $ find | grep config.log
./build/linux-x86_64-normal-server-fastdebug/config.log

This block was accidentally dropped:
 http://hg.openjdk.java.net/jdk8u/jdk8u-dev/rev/7cf12efdd88d#l3.11