Need reviewer: Turn off warnings for mapfiles in fastdebug builds

[Kelly O'Hair]

Need reviewer: Turn off warnings for mapfiles in fastdebug builds

The mapfiles are generally not used on fastdebug or debug builds, this just turns off the
warning in these cases, making it just an informative piece of information.

7033960: Do not check for mapfiles when fastdebug building
http://cr.openjdk.java.net/~ohair/openjdk7/jdk7-build-mapfile-warning/webrev/

-kto