RFR: 8014404: Debug flag not added to jdk native compile when --enable-debug is set

[Tim Bell]

Erik:

> When configuring with --enable-debug, no -g flag is added to the jdk 
> native compilations. This patch fixes this and tries to mimic the 
> settings of -g and optimization flags with the old build as close as I 
> could manage.
>
> http://cr.openjdk.java.net/~erikj/8014404/webrev.root.01

Looks good.

Tim