Revert "Build riscv64 with thin LTO"

This reverts commit 17c9c2a5b5779f7f5a9244be1e4bb7c0b8f3999e.

Reason for revert: Wait until new toolchain with linker fix las landed (https://android-review.git.corp.google.com/c/toolchain/llvm_android/+/2424081)

Change-Id: I05b14c12ac93182dd93c5b490f260071c6d3a090
diff --git a/cc/lto.go b/cc/lto.go
index 581856b..1afa1dd 100644
--- a/cc/lto.go
+++ b/cc/lto.go
@@ -91,6 +91,11 @@
 		return flags
 	}
 
+	// TODO(b/254713216): LTO doesn't work on riscv64 yet.
+	if ctx.Arch().ArchType == android.Riscv64 {
+		return flags
+	}
+
 	if lto.LTO(ctx) {
 		var ltoCFlag string
 		var ltoLdFlag string