Allow SCS for riscv64 too.

Bug: https://github.com/google/android-riscv64/issues/55
Test: treehugger
Change-Id: I319fc662c1dd6083757f78b8d91ec2775ef94a46
diff --git a/cc/sanitize.go b/cc/sanitize.go
index 66f459a..a31a358 100644
--- a/cc/sanitize.go
+++ b/cc/sanitize.go
@@ -254,7 +254,7 @@
 	// This should not be used in Android 11+ : https://source.android.com/devices/tech/debug/scudo
 	// deprecated
 	Scudo *bool `android:"arch_variant"`
-	// shadow-call-stack sanitizer, only available on arm64
+	// shadow-call-stack sanitizer, only available on arm64/riscv64.
 	Scs *bool `android:"arch_variant"`
 	// Memory-tagging, only available on arm64
 	// if diag.memtag unset or false, enables async memory tagging
@@ -593,8 +593,8 @@
 		s.Hwaddress = nil
 	}
 
-	// SCS is only implemented on AArch64.
-	if ctx.Arch().ArchType != android.Arm64 || !ctx.toolchain().Bionic() {
+	// SCS is only implemented on AArch64/riscv64.
+	if (ctx.Arch().ArchType != android.Arm64 && ctx.Arch().ArchType != android.Riscv64) || !ctx.toolchain().Bionic() {
 		s.Scs = nil
 	}