build: config: add v8 target cpu for riscv64

Signed-off-by: Tien Hock Loh <tienhock.loh@starfivetech.com>
Signed-off-by: Rebecca Chang Swee Fun <rebecca.chang@starfivetech.com>
Change-Id: Ie2f44269b48602ae41a5fdcc43913e55022e8410
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3859046
Commit-Queue: Alan Zhao <ayzhao@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1043788}
NOKEYCHECK=True
GitOrigin-RevId: 4fc712665919a969f976b7ed78d3a0d38bab5fd3

config/v8_target_cpu.gni

@@ -44,6 +44,9 @@ if (v8_target_cpu == "") {
   } else if (current_toolchain ==
              "//build/toolchain/linux:clang_x86_v8_mipsel") {
     v8_target_cpu = "mipsel"
+  } else if (current_toolchain ==
+             "//build/toolchain/linux:clang_x64_v8_riscv64") {
+    v8_target_cpu = "riscv64"
   } else if (is_msan) {
     # If we're running under a sanitizer, if we configure v8 to generate
     # code that will be run under a simulator, then the generated code