runtime: change maxSearchAddr into a helper function
This avoids a dependency on the compiler statically initializing
maxSearchAddr, which is necessary so we can disable the (overly
aggressive and spec non-conforming) optimizations in cmd/compile and
gccgo.
Updates #51913.
Change-Id: I424e62c81c722bb179ed8d2d8e188274a1aeb7b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/396194 Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>