RFR(M): 8202713: Create a MacroAssembler::access_load/store_at wrapper for S390 and PPC

[Doerr, Martin]

Hi Erik,

thanks for creating the bug. It makes sense to use load/store_heap_oop like on the other platforms.
It will especially be useful when we add support for a GC with load barriers.

Here's the webrev:
http://cr.openjdk.java.net/~mdoerr/8202713_ppc64_s390_masm_access/webrev.00/

Please review.

Best regards,
Martin