RFR: 8216385: ZGC: Fix building without C2

[Erik Osterlund]

+1

/Erik

> On 8 Jan 2019, at 21:14, Per Liden <per.liden at oracle.com> wrote:
> 
> Building without C2 enabled (e.g. a client VM variant) fails after JDK-8215547, which introduced unconditional uses of "MaxVectorSize", a symbol only available when C2 is enabled.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8216385
> Webrev: http://cr.openjdk.java.net/~pliden/8216385/webrev.0
> 
> /Per