Only export public symbols.

[ Merge of http://go/wvgerrit/67923 ]

Before, all symbols were being exported in the dynamic library.  Now
only the public symbols are.  This no longer has the unit tests load
the dynamic library, so we lose testing the dynamic integration; but
the unit tests use a lot of internals, even the top-level CDM ones.

Bug: 69271232
Bug: 69548115
Test: WV unit/integration tests
Change-Id: I62919937277ec785aca1f8b36b28caa2f9d8f3ea

libwvdrmengine/cdm/util/include/file_store.h

@@ -13,11 +13,12 @@
 #include <vector>
 
 #include "disallow_copy_and_assign.h"
+#include "util_common.h"
 
 namespace wvcdm {
 
 // File class. The implementation is platform dependent.
-class File {
+class CORE_UTIL_EXPORT File {
  public:
   File() {}
   virtual ~File() {}
@@ -28,7 +29,7 @@ class File {
   CORE_DISALLOW_COPY_AND_ASSIGN(File);
 };
 
-class FileSystem {
+class CORE_UTIL_EXPORT FileSystem {
  public:
   FileSystem();
   FileSystem(const std::string& origin, void* extra_data);