Fix(Build): with Clang < 20 by removing unsupported compiler flags

The -fextend-variable-liveness=none flag is supported only in Clang 20+,
was added to Chromium to workaround compile error in fuchsia-fyi-x64-dbg-persistent-emulator. ref: https://chromium.googlesource.com/chromium/src.git/+/baa29fd5df8262a9d5aebb9cc3d9d047a39add4c
This updates our clang-19-compat.patch to remove all instances of this unsupported flag, allowing Chromium to build successfully with our current Clang version.

Signed-off-by: Debasish Biswas <debasishbsws.dev@gmail.com>

Author: debasishbsws

chromium/clang-19-compat.patch

@@ -1,13 +1,31 @@
 Description: Disable Clang >= 20 compiler options until packaged
+The -fextend-variable-liveness=none flag was added to Chromium to work with newer versions of Clang (likely Clang 20+)
+as -fextend-variable-liveness=none flag is not available in Clang<20 
+It is a new compiler flag: https://releases.llvm.org/20.1.0/tools/clang/docs/ReleaseNotes.html#new-compiler-flags
+This whole patch can be removed once we package Clang 20+ in the future.
 Author: James Page <james.page@chainguard.dev>
 
 --- a/build/config/compiler/BUILD.gn.orig	2025-05-12 16:11:29.949768459 +0100
 +++ b/build/config/compiler/BUILD.gn	2025-05-12 16:12:14.385296607 +0100
-@@ -312,7 +312,6 @@ config("compiler") {
+@@ -313,7 +313,6 @@ config("compiler") {
      ":compiler_cpu_abi",
      ":compiler_codegen",
      ":compiler_deterministic",
 -    ":clang_warning_suppression",
    ]
 
    # Here we enable -fno-delete-null-pointer-checks, which makes various nullptr
+@@ -623,13 +622,6 @@ config("compiler") {
+         default_toolchain != "//build/toolchain/cros:target") {
+       cflags += [ "-Wa,--crel,--allow-experimental-crel" ]
+     }
+-
+-    # TODO(crbug.com/413427035): Remove once
+-    # https://github.com/llvm/llvm-project/pull/136867/ is landed.
+-    if (!is_win && !llvm_android_mainline &&
+-        default_toolchain != "//build/toolchain/cros:target") {
+-      cflags += [ "-fextend-variable-liveness=none" ]
+-    }
+   }
+ 
+   # C11/C++11 compiler flags setup.

chromium/gperf.patch

@@ -5,7 +5,7 @@ gperf massaging that causes the problem.
 
 --- a/third_party/blink/renderer/build/scripts/gperf.py
 +++ b/third_party/blink/renderer/build/scripts/gperf.py
-@@ -28,27 +28,7 @@ def generate_gperf(gperf_path, gperf_input, gperf_args):
+@@ -28,27 +28,6 @@ def generate_gperf(gperf_path, gperf_input, gperf_args):
              stdout=subprocess.PIPE,
              universal_newlines=True)
          gperf_output = gperf.communicate(gperf_input)[0]