gcc/testsuite/go: increase memory in issue4085b.go

[CHIGOT, CLEMENT via Gcc-patches]

Description: 
  On aix/ppc64, it's possible to allocate an array of 1<<50 int, because of the
  wider address space. Thus, increase it to 1<<59 like in Golang toolchain in
  order to trigger the panic.

Changelog:
2020-05-19 Clement Chigot <clement.chi...@atos.net>
  * go.test/test/fixedbugs/issue4085b.go: increase the size of n2 in 64bit


Please apply for me if approved.
Could it be backported in gcc-8 and gcc-9 branch too ? 

Thanks,
Clément Chigot

gcc-8.4.0-gcc-testsuite-go-increase-memory-in-issue4085b.go.patch
Description: gcc-8.4.0-gcc-testsuite-go-increase-memory-in-issue4085b.go.patch