hg: jdk/sandbox: Trying to clear up gcc warnings as well.

[magnus.ihse.bursie at oracle.com]

Changeset: bdf8f77aad3a
Author:    ihse
Date:      2018-03-01 17:00 +0100
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/bdf8f77aad3a

Trying to clear up gcc warnings as well.

! make/autoconf/flags-cflags.m4
! src/hotspot/os/linux/os_linux.cpp
! src/hotspot/share/oops/klass.cpp
! src/hotspot/share/opto/machnode.hpp
! src/hotspot/share/prims/jvm.cpp