RFR: JDK-8244036 Refresh SetupJavaCompilation, and remove support for sjavac

[Florian Weimer]

* Magnus Ihse Bursie:

> The code for setting up Java compilation has long been quite hard to 
> understand, and has a tricky API. Part of this is due to the support for 
> the sjavac ("smart javac") system. We do not use sjavac anymore, and it 
> has not been tested for long. Part of the sjavac effort was extracted 
> into the "depend" javac plugin, and another part ended up as the java 
> server, both of which we still use.

This commit:

# HG changeset patch
# User ihse
# Date 1588142957 -7200
#      Wed Apr 29 08:49:17 2020 +0200
# Node ID a8e4856be54f73225780a56b2b6ee9cc1e12ab8f
# Parent  f53590a82709caf92213106954eab2bdc97cc498
8244036: Refresh SetupJavaCompilation, and remove support for sjavac
Reviewed-by: erikj

appears to have regressed build time (“time make jdk-image”) by
roughly one third, on an x86-64 machine with 8 cores/16 threads.
The configure arguments are “--with-zlib=system --with-lcms=system”,
so nothing sjavac-related as far as I can see.

Is this expected?