Misc Windows fixes.

(This is a merge of http://go/wvgerrit/70324)

- Add build settings for Windows.
- Conditionally add pthread.
- Add dummy DLLMain method.
- Fix #if checks for Windows.
- Remove designated initializers which aren't supported in MSVC.
- Remove variable length array.

Test: Android Unit Tests
Bug: 122953649
Change-Id: I14f16e7ce4b3ff17ee0139ea6c2f7243ae999aa1

libwvdrmengine/oemcrypto/test/oec_session_util.h

@@ -8,6 +8,7 @@
 // OEMCrypto unit tests
 //
 #include <openssl/rsa.h>
+#include <time.h>
 #include <string>
 #include <vector>