RFR: JDK-8232133: Change to GCC 8.3 for building on Linux at Oracle

[Kim Barrett]

> On Oct 10, 2019, at 2:27 PM, Erik Joelsson <erik.joelsson at oracle.com> wrote:
> 
> Updating defaults in devkit creator makefiles. Also remembering to update building.md this time.
> 
> Webrev: http://cr.openjdk.java.net/~erikj/8232133/webrev.01/
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8232133
> 
> /Erik

doc/building.md
 341 The JDK is currently known to be able to compile with at least version 7.4 of
 342 gcc.

Maybe things like the above should get cleaned up while you are here.

Other than that, looks good to me.  I don’t need another webrev for version updates
like that mentioned above.