[build] //src/sys/build -> //build/components

Change-Id: I1db9eaddfcdbb9a4d1aa080a31f60150ba2366f4
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/github.com/kmackay/micro-ecc/+/517008
Reviewed-by: Shai Barack <shayba@google.com>