test: bump array size in fixedbugs/issue39292.go

test: bump array size in fixedbugs/issue39292.go

The previous array length was large enough to exceed
maxImplicitStackSize on 64-bit architectures, but not on 32-bit
architectures.

Fixes #40808.

Change-Id: I69e9abb447454b2e7875ba503a0cb772e965ae31
Reviewed-on: https://go-review.googlesource.com/c/go/+/248680
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>