RFR : JDK-8032045 : (m/l) Enable compiler and linker safety switches for debug builds

[Mike Duigou]

Hello all;

After some additional work this changeset appears to finally complete. This is your very last chance to review and further extend the saga!

jbsbug: https://bugs.openjdk.java.net/browse/JDK-8032045
webrev:http://cr.openjdk.java.net/~mduigou/JDK-8032045/9/webrev/

The changes since the last version remove some bash4.0-isms, backout an unnecessary change to the optimization level of HIGHEST and backout a change that was causing problems on MacOS. The later has been moved to a separate issue, 8046397.

I've completed product and fastdebug builds and test on all supported platforms including embedded and slowdebug builds on linux and macos with no apparent regressions.

Cheers,

Mike