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

[Erik Joelsson]

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/
/Erik