Disable LTO and CFI for riscv64

Building with LTO and CFI enabled for riscv64 causes link failures:
ld.lld: error: lto.tmp: cannot link object files with different floating-point ABI
ld.lld: error: undefined symbol: guard variable for android::hardware::BufferedTextOutput::getBuffer() const::ts

Disable them for now.

Test: lunch aosp_riscv64-userdebug && m ALLOW_MISSING_DEPENDENCIES=true ndk_sysroot
Change-Id: I3489952abebeeb3f4de664fd3e436232aac298d7
diff --git a/cc/sanitize.go b/cc/sanitize.go
index 0b47f0e..d39b0eb 100644
--- a/cc/sanitize.go
+++ b/cc/sanitize.go
@@ -511,6 +511,12 @@
 		s.Integer_overflow = nil
 	}
 
+	// CFI doesn't work for riscv64 yet because LTO doesn't work.
+	if ctx.Arch().ArchType == android.Riscv64 {
+		s.Cfi = nil
+		s.Diag.Cfi = nil
+	}
+
 	// Disable CFI for musl
 	if ctx.toolchain().Musl() {
 		s.Cfi = nil