RFR: 8224214: [AIX] Remove support for legacy xlc compiler

[Kim Barrett]

> On Aug 29, 2019, at 11:41 AM, Baesken, Matthias <matthias.baesken at sap.com> wrote:
> 
> Hi Martin, I agree  about the m4 files .
> New webrev , this additionally touches    toolchain.m4  and flags-cflags.m4
> 
> http://cr.openjdk.java.net/~mbaesken/webrevs/8224214.1/

This looks good.  Thanks for removing the DR45 workarounds.

You should probably get a build person to look at the additional build changes though.