RFR: JDK-8187676: Disable uninitialized warnings for two files until proper fix available

[Tim Bell]

Erik:
> In preparation for upgrading the toolchains used at Oracle, we need the
> build to be clean with the new compiler versions. On Linux, we are
> currently aiming at GCC 7.3. In hotspot, two files generate warnings
> when using this compiler. I found this issue already filed with a patch
> for disabling the warnings and the related issue JDK-8160404 which will
> deal with actually fixing the problem. I would like to push the
> disabling of the warnings ASAP so that the compiler upgrade project can
> continue unhindered.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8187676
>
> Webrev: http://cr.openjdk.java.net/~ehelin/8187676/00/

Looks good.

/Tim