Hide some SyzyASan specific code behind an '#if defined(COMPILER_MSVC)'.

base/debug/asan_invalid_access.cc

Index: base/debug/asan_invalid_access.cc
diff --git a/base/debug/asan_invalid_access.cc b/base/debug/asan_invalid_access.cc
index 040b937613b89af815d2557e814f8cfbb9772268..68f45652044acaf1e86f7ac6f3f2e38aaacee65d 100644
--- a/base/debug/asan_invalid_access.cc
+++ b/base/debug/asan_invalid_access.cc
@@ -16,7 +16,7 @@ namespace debug {
 
 namespace {
 
-#if defined(SYZYASAN)
+#if defined(SYZYASAN) && defined(COMPILER_MSVC)
 // Disable warning C4530: "C++ exception handler used, but unwind semantics are
 // not enabled". We don't want to change the compilation flags just for this
 // test, and no exception should be triggered here, so this warning has no value
@@ -91,7 +91,7 @@ void AsanHeapUseAfterFree() {
 
 #endif  // ADDRESS_SANITIZER || SYZYASAN
 
-#if defined(SYZYASAN)
+#if defined(SYZYASAN) && defined(COMPILER_MSVC)
 void AsanCorruptHeapBlock() {
   CorruptMemoryBlock(false);
 }