RFR: 8245098: Make SafeFetch32/N available earlier

[Kim Barrett]

> On May 15, 2020, at 8:03 AM, Per Liden <per.liden at oracle.com> wrote:
> 
> We have a need for SafeFetch32 during initializing of ZGC (see [1]). However, the SafeFetch32/N stubs are currently generated too late, in the stubRoutines_init2() phase, which is after the GC has been initialized. I propose we move the initialization of these stubs to the stubRoutines_init1() phase, which is before the GC has been initialized, to make them available during GC initialization.
> 
> Please note that this patch touches platforms I can't easily test (x86-32, arm, ppc, s390). If you have access to one of those machines, I would appreciate if you could do some light verification.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8245098
> Webrev: http://cr.openjdk.java.net/~pliden/8245098/webrev.0
> Testing: Tier1-3 on all Oracle supported platforms.
> 
> /Per
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8245106

Looks good.