netstack: make go:linkname work for all architectures

The //go:linkname directive requires the presence of
assembly files in the package. Even an empty file will do.
There was an empty assembly file commit_arm64.s, but
that is limited to GOARCH=arm64. Renaming to empty.s will
remove the unnecessary build constraint and allow building
netstack for other architectures than amd64 and arm64.

Without this, building directly with go (not bazel)
for e.g., GOARCH=arm gives:

sleep/sleep_unsafe.go:88:6: missing function body
sleep/sleep_unsafe.go:91:6: missing function body

Change-Id: I29d1d13e1ff31506a174d4595b8cd57fa58bf52b
PiperOrigin-RevId: 214820299

0 files changed, 0 insertions, 0 deletions