crypto/internal/fips: add service indicator mechanism

crypto/internal/fips: add service indicator mechanism

Placed the fipsIndicator field in some 64-bit alignment padding in the g
struct to avoid growing per-goroutine memory requirements on 64-bit
targets.

Fixes #69911
Updates #69536

Change-Id: I176419d0e3814574758cb88a47340a944f405604
Reviewed-on: https://go-review.googlesource.com/c/go/+/620795
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Derek Parker <parkerderek86@gmail.com>