Add a new x86(_64) arch variant "goldmont-without-xsaves"

Its target arch is goldmont, but without xsaves support.
This ensures efficient execution on a broad range of Intel/AMD CPUs used
in Chromebooks, including those lacking xsaves support.
(e.g. Kaby Lake, Gemini Lake, Alder Lake and AMD Zen series)

Bug: 314243939
Test: Build an image with TARGET_ARCH_VARIANT:=goldmont-without-xsaves
Change-Id: I9963cc3356394815f068fc998a9708bdb30c8266

cc/config/x86_device.go

@@ -56,6 +56,10 @@ var (
 		"goldmont-plus": []string{
 			"-march=goldmont-plus",
 		},
+		"goldmont-without-xsaves": []string{
+			"-march=goldmont",
+			"-mno-xsaves",
+		},
 		"haswell": []string{
 			"-march=core-avx2",
 		},