[cppgc][unittests] Only expect guard pages support on 4k platforms.

Loong64 supports 4K-64K OS pages
Fix loong64 unittests PlatformUsesGuardPages failure

Change-Id: I1451685828ef1d857b7d2af3f1810286f84bdc50
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3299672Reviewed-by: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Cr-Commit-Position: refs/heads/main@{#78120}

AUTHORS

@@ -149,6 +149,7 @@ Loo Rong Jie <loorongjie@gmail.com>
 Lu Yahan <yahan@iscas.ac.cn>
 Luis Reis <luis.m.reis@gmail.com>
 Luke Zarko <lukezarko@gmail.com>
+Ma Aiguo <maaiguo@uniontech.com>
 Maciej Małecki <me@mmalecki.com>
 Marcel Laverdet <marcel@laverdet.com>
 Marcin Cieślak <saper@marcincieslak.com>

test/unittests/heap/cppgc/page-memory-unittest.cc

@@ -121,7 +121,7 @@ TEST(PageMemoryRegionTest, PlatformUsesGuardPages) {
   v8::base::PageAllocator allocator;
 #if defined(V8_HOST_ARCH_PPC64) && !defined(_AIX)
   EXPECT_FALSE(SupportsCommittingGuardPages(allocator));
-#elif defined(V8_HOST_ARCH_ARM64)
+#elif defined(V8_HOST_ARCH_ARM64) || defined(V8_HOST_ARCH_LOONG64)
   if (allocator.CommitPageSize() == 4096) {
     EXPECT_TRUE(SupportsCommittingGuardPages(allocator));
   } else {