Replace PST Report with buffer

Merge from Widevine repo of http://go/wvgerrit/23044

On some platforms, the compiler will not pack structures.  This CL
replaces the OECrypto_PST_Report packed structure with a simple buffer
of uint8_t.  This changes the signature of OEMCrypto_ReportUsage as
part of OEMCrypto v13.

There is also a new wrapper class that test code, the mock, and debug
code can use to access data in the report.

The old packed structure definition is moved to the level 3, where we
use a compiler that packs sructs when asked nicely.

arm/libwvlevel3.a  Level3 Library 4445 Jan 20 2017 11:29:15
x86/libwvlevel3.a  Level3 Library 4464 Jan 20 2017 11:10:49
mips/libwvlevel3.a  Level3 Library 4465 Jan 20 2017 10:56:08

b/32180083

Change-Id: Ie138f034cb12780a2f8636888cebf022c52169e5

libwvdrmengine/oemcrypto/test/oec_session_util.h

@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "oec_device_features.h"
+#include "pst_report.h"
 #include "wv_cdm_constants.h"
 
 using namespace std;
@@ -253,9 +254,11 @@ class Session {
   // order to verify signatures.
   void GenerateReport(const std::string& pst, bool expect_success = true,
                       Session* other = 0);
-  // Returns a pointer to the usage report generated by the previous call to
-  // GenerateReport.
-  OEMCrypto_PST_Report* pst_report();
+  // Returns a pointer-like thing to the usage report generated by the previous
+  // call to GenerateReport.
+  wvcdm::Unpacked_PST_Report pst_report() {
+    return wvcdm::Unpacked_PST_Report(&pst_report_buffer_[0]);
+  }
   // Creates a signed delete usage table entry message and calls
   // OEMCrypto_DeleteUsageEntry on it.
   void DeleteEntry(const std::string& pst);