[heap] V8_OS_MACOSX -> V8_OS_MACOS

This renaming was missed in
https://chromium-review.googlesource.com/c/v8/v8/+/3468577, because the
code adding these #ifdef blocks landed in-between the renaming change
being uploaded and landed.

Bug: chromium:1298417
Change-Id: I8c2e951099dafcce7e19a59e40e36f308e2ed867
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3498349Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Benoit Lize <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79345}

src/heap/cppgc/globals.h

@@ -43,7 +43,7 @@ constexpr size_t kPageSize = 1 << kPageSizeLog2;
 constexpr size_t kPageOffsetMask = kPageSize - 1;
 constexpr size_t kPageBaseMask = ~kPageOffsetMask;
 
-#if defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_MACOSX)
+#if defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_MACOS)
 // No guard pages on ARM64 macOS. This target has 16 kiB pages, meaning that
 // the guard pages do not protect anything, since there is no inaccessible
 // region surrounding the allocation.

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

@@ -116,7 +116,7 @@ TEST(PageMemoryRegionTest, LargePageMemoryRegion) {
 }
 
 // See the comment in globals.h when setting |kGuardPageSize| for details.
-#if !(defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_MACOSX))
+#if !(defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_MACOS))
 TEST(PageMemoryRegionTest, PlatformUsesGuardPages) {
   // This tests that the testing allocator actually uses protected guard
   // regions.
@@ -134,7 +134,7 @@ TEST(PageMemoryRegionTest, PlatformUsesGuardPages) {
   EXPECT_TRUE(SupportsCommittingGuardPages(allocator));
 #endif
 }
-#endif  // !(defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_MACOSX))
+#endif  // !(defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_MACOS))
 
 namespace {