math/bits: note that functions here may be compiler intrinsics
It was noted in the go1.9 release notes that functions in math/bits
may be implemented by compiler intrinsics, but this never made it to
the documentation.
This change adapts the wording of the release notes and puts it in the
documentation for math/bits.
Change-Id: Ibeea88eaf7df10952cbe670885e910ac30b49d55
Reviewed-on: https://go-review.googlesource.com/c/go/+/444035 Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Filippo Valsorda <filippo@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>