Add a mean to disable the has_memory_tagging condition so the ebuild
can disable it where needed. Just a quick solution, ideally Gn itself
should be able to figure this out.

https://bugs.gentoo.org/981510
https://gitlab.alpinelinux.org/alpine/aports/-/blob/master/community/chromium/partalloc-no-tagging-arm64.patch
--- a/src/3rdparty/chromium/base/allocator/partition_allocator/partition_alloc.gni
+++ b/src/3rdparty/chromium/base/allocator/partition_allocator/partition_alloc.gni
@@ -88,6 +88,10 @@
 use_large_empty_slot_span_ring = true
 
+declare_args() {
+  allow_memory_tagging = true
+}
+
 has_memory_tagging = current_cpu == "arm64" && is_clang && !is_asan &&
-                     !is_hwasan && (is_linux || is_android)
+                     !is_hwasan && (is_linux || is_android) && allow_memory_tagging
 
 declare_args() {