updpatch: chromium 129.0.6668.58-1

Note: the patch is tested against 129.0.6668.42-1

- Drop v8 version bump and patch.
- Add new fixes. See also https://www.kxxt.dev/blog/cross-compile-chromium-for-riscv/
- Enable `is_clang` to workaround GNU ld cannot link `flatc`, Relocation
  truncated to fit.
  - This change necessitates the stacked patch
    compiler-rt-riscv.patch, which is applied after Arch's compiler-rt
    patch.
- Regenerate ffmpeg patch.

chromium/cargo_crate-riscv-pointer-width.patch

@@ -0,0 +1,31 @@
+From c50dab84e0c911f7b89532700fca27d42a77b3c1 Mon Sep 17 00:00:00 2001
+From: kxxt <rsworktech@outlook.com>
+Date: Fri, 13 Sep 2024 12:48:44 +0000
+Subject: [PATCH] cargo_crate.gni: add riscv64 and loong64 cases
+
+This CL syncs the condition of 64 bit pointer with
+https://github.com/chromium/chromium/blob/31f058a669fd063cab3439df5c877ed3005d9832/base/allocator/partition_allocator/partition_alloc.gni#L21-L24
+
+Bug: none
+Change-Id: Id2f1cfaa0c5167fb61c74505aba03716337b071f
+Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5850670
+Commit-Queue: Nico Weber <thakis@chromium.org>
+Reviewed-by: Nico Weber <thakis@chromium.org>
+Reviewed-by: Arthur Eubanks <aeubanks@google.com>
+Cr-Commit-Position: refs/heads/main@{#1355138}
+---
+
+diff --git a/build/rust/cargo_crate.gni b/build/rust/cargo_crate.gni
+index e5d1b2f8..7290451 100644
+--- a/build/rust/cargo_crate.gni
++++ b/build/rust/cargo_crate.gni
+@@ -429,7 +429,8 @@
+           rust_abi_target,
+         ]
+       }
+-      if (current_cpu == "arm64" || current_cpu == "x64") {
++      if (current_cpu == "arm64" || current_cpu == "x64" ||
++          current_cpu == "loong64" || current_cpu == "riscv64") {
+         args += [
+           "--pointer-width",
+           "64",

chromium/compiler-rt-riscv.patch

@@ -0,0 +1,12 @@
+--- build/config/clang/BUILD.gn.orig	2024-09-17 09:40:39.225707556 +0200
++++ build/config/clang/BUILD.gn	2024-09-17 09:42:35.703531635 +0200
+@@ -201,6 +201,9 @@
+         } else if (current_cpu == "arm64") {
+           _dir = "aarch64-unknown-linux-gnu"
+           _suffix = "-aarch64"
++        } else if (current_cpu == "riscv64") {
++          _dir = "riscv64-unknown-linux-gnu"
++          _suffix = "-riscv64"
+         } else {
+           assert(false)  # Unhandled cpu type
+         }