[build] Make analyze_snapshot GN target available for riscv64.

Flutter refers to this target.

Bug: https://github.com/flutter/flutter/issues/99963
Bug: https://github.com/flutter/flutter/issues/117973
Change-Id: I7a4464216c50f7248fc73664af1c5b217d1a7b8d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/341101
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
diff --git a/runtime/runtime_args.gni b/runtime/runtime_args.gni
index aedfdcc..882bf3b 100644
--- a/runtime/runtime_args.gni
+++ b/runtime/runtime_args.gni
@@ -93,5 +93,6 @@
   build_analyze_snapshot =
       (target_os == "linux" || target_os == "android" ||
        target_os == "fuchsia") &&
-      (dart_target_arch == "x64" || dart_target_arch == "arm64")
+      (dart_target_arch == "x64" || dart_target_arch == "arm64" ||
+       dart_target_arch == "riscv64")
 }