cmd/link: suppress -no_pie deprecation warning on darwin

Apparently the new darwin linker starts to emit a warning about
-no_pie deprecation. Maybe we want to switch to PIE by default.
For now, suppress the warning. This also makes it easier for
backporting to previous releases.

For #54482.

Change-Id: I1a3b74c237a9d00ec3b030fc3a9940a31e5cd37e
Reviewed-on: https://go-review.googlesource.com/c/go/+/430937
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/link/internal/ld/lib.go

@@ -1775,6 +1775,13 @@ func (ctxt *Link) hostlink() {
 	if len(out) > 0 {
 		// always print external output even if the command is successful, so that we don't
 		// swallow linker warnings (see https://golang.org/issue/17935).
+		if ctxt.IsDarwin() && ctxt.IsAMD64() {
+			const noPieWarning = "ld: warning: -no_pie is deprecated when targeting new OS versions\n"
+			if i := bytes.Index(out, []byte(noPieWarning)); i >= 0 {
+				// swallow -no_pie deprecation warning, issue 54482
+				out = append(out[:i], out[i+len(noPieWarning):]...)
+			}
+		}
 		ctxt.Logf("%s", out)
 	}