netxlite: call getaddrinfo and handle platform-specific oddities (#764)

This commit changes our system resolver to call getaddrinfo directly when CGO is enabled. This change allows us to:

1. obtain the CNAME easily

2. obtain the real getaddrinfo retval

3. handle platform specific oddities such as `EAI_NODATA`
returned on Android devices

See https://github.com/ooni/probe/issues/2029 and https://github.com/ooni/probe/issues/2029#issuecomment-1140258729 in particular.

See https://github.com/ooni/probe/issues/2033 for documentation regarding the desire to see `getaddrinfo`'s retval.

See https://github.com/ooni/probe/issues/2118 for possible follow-up changes.

internal/netxlite/getaddrinfo_otherwise.go

@@ -0,0 +1,12 @@
+//go:build !cgo
+
+package netxlite
+
+import (
+	"context"
+	"net"
+)
+
+func getaddrinfoLookupANY(ctx context.Context, domain string) ([]string, string, error) {
+	return net.DefaultResolver.LookupHost(ctx, domain)
+}