hg: graal/graal-compiler: use JVMCI_VERSION constant to avoid too much eagerness when loading mx_graal_8

[doug.simon at oracle.com]

Changeset: ed6a5ffb2e9c
Author:    Doug Simon <doug.simon at oracle.com>
Date:      2016-01-19 12:04 +0100
URL:       http://hg.openjdk.java.net/graal/graal-compiler/rev/ed6a5ffb2e9c

use JVMCI_VERSION constant to avoid too much eagerness when loading mx_graal_8

! mx.graal/mx_graal_8.py
! mx.graal/suite.py