Remove usage of COMPILER_MSVC in Bazel and ijar

Convert most `COMPILER_MSVC` to `_WIN32` (as they apply to Windows platform, not MSVC compiler). Only `src/tools/singlejar/zip_headers.h` and `src/main/cpp/util/md5.h` actually need `_MSC_VER`.

`COMPILER_MSVC` in `third_party/protobuf` are not removed. They can be fixed by updating dependency to newer version.

/cc @meteorcloudy

Closes #5350.

Change-Id: Ibc131abfaf34a0cb2bd338549983ea9d28eaabfe
PiperOrigin-RevId: 200019793
diff --git a/src/test/cpp/util/windows_test_util_test.cc b/src/test/cpp/util/windows_test_util_test.cc
index d777a91..7ee97f1 100644
--- a/src/test/cpp/util/windows_test_util_test.cc
+++ b/src/test/cpp/util/windows_test_util_test.cc
@@ -18,9 +18,9 @@
 #include "googletest/include/gtest/gtest.h"
 #include "src/test/cpp/util/windows_test_util.h"
 
-#if !defined(COMPILER_MSVC) && !defined(__CYGWIN__)
+#if !defined(_WIN32) && !defined(__CYGWIN__)
 #error("This test should only be run on Windows")
-#endif  // !defined(COMPILER_MSVC) && !defined(__CYGWIN__)
+#endif  // !defined(_WIN32) && !defined(__CYGWIN__)
 
 namespace blaze_util {