cmd/link/internal/ld: unify OS/SDK versions for macOS linking

Go 1.23 will require macOS 11 Big Sur or later, even on AMD64.
The comment here suggests the main requirement for the OS and
SDK version is to be recent enough not to break Apple signing,
and recent enough not to cause other problems.

For now, this CL simplifies the code by merging the ARM64 and
AMD64 cases into one, given 1.23 will be the first Go release
with a common minimum macOS version for both architectures so
there's no need to treat them separately here.

For golang#64207.

Change-Id: I821fcb9a2a316de0703833c8a75abcbaa10b17a3
Cq-Include-Trybots: luci.golang.try:gotip-darwin-amd64_11,gotip-darwin-amd64_14,gotip-darwin-arm64_11,gotip-darwin-arm64_13
Reviewed-on: https://go-review.googlesource.com/c/go/+/563857
Reviewed-by: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

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

@@ -478,13 +478,11 @@ func (ctxt *Link) domacho() {
 		if ctxt.LinkMode == LinkInternal && machoPlatform == PLATFORM_MACOS {
 			var version uint32
 			switch ctxt.Arch.Family {
-			case sys.AMD64:
+			case sys.ARM64, sys.AMD64:
 				// This must be fairly recent for Apple signing (go.dev/issue/30488).
 				// Having too old a version here was also implicated in some problems
 				// calling into macOS libraries (go.dev/issue/56784).
 				// In general this can be the most recent supported macOS version.
-				version = 10<<16 | 13<<8 | 0<<0 // 10.13.0
-			case sys.ARM64:
 				version = 11<<16 | 0<<8 | 0<<0 // 11.0.0
 			}
 			ml := newMachoLoad(ctxt.Arch, LC_BUILD_VERSION, 4)

src/cmd/link/link_test.go

@@ -388,9 +388,9 @@ func TestMachOBuildVersion(t *testing.T) {
 	found := false
 	const LC_BUILD_VERSION = 0x32
 	checkMin := func(ver uint32) {
-		major, minor := (ver>>16)&0xff, (ver>>8)&0xff
-		if major != 10 || minor < 9 {
-			t.Errorf("LC_BUILD_VERSION version %d.%d < 10.9", major, minor)
+		major, minor, patch := (ver>>16)&0xff, (ver>>8)&0xff, (ver>>0)&0xff
+		if major < 11 {
+			t.Errorf("LC_BUILD_VERSION version %d.%d.%d < 11.0.0", major, minor, patch)
 		}
 	}
 	for _, cmd := range exem.Loads {