It's still Windows-only for now but it's easy to de-Windows-ify when needed.
Moving it out of corp repo and into tailscale/tailscale so we can use
it in ipnserver.BabysitProc.
Updates #726
LogHeap no longer logs to os.Stderr and instead uploads
the heap profile by means of an HTTP POST request to the
target URL endpoint.
While here, also ensured that an error from pprof.WriteHeapProfile
isn't ignored and will prevent the HTTP request from being made
if non-nil.
Signed-off-by: Emmanuel T Odeke <emmanuel@orijtech.com>
