git: openjdk/jdk: 8273072: Avoid using += in configure

[Magnus Ihse Bursie]

Changeset: a033aa5a
Author:    Magnus Ihse Bursie <ihse at openjdk.org>
Date:      2021-08-27 13:53:33 +0000
URL:       https://git.openjdk.java.net/jdk/commit/a033aa5a3d9c63d72d11af218b9896b037fbd8de

8273072: Avoid using += in configure

Reviewed-by: dholmes, jiefu

! make/autoconf/flags-cflags.m4
! make/autoconf/flags-other.m4
! make/autoconf/jdk-version.m4
! make/devkit/createMacosxDevkit.sh