Rework platform version to hide codenames.

The public platform version no longer can be a codename, it is
always the most recently released platform.  A new build property
and API provides either the offical version or the current codename
as appropriate.  This will avoid breaking apps that look at the
platform version while development is under a codename.

Bug:  143175463
Test: manual
Change-Id: I8dec42edf5a4a6184156643c91073e33936fae56

webrtc/examples/androidapp/src/org/appspot/apprtc/util/AppRTCUtils.java

@@ -55,7 +55,7 @@ public final class AppRTCUtils {
   /** Information about the current build, taken from system properties. */
   public static void logDeviceInfo(String tag) {
     Log.d(tag, "Android SDK: " + Build.VERSION.SDK_INT + ", "
-        + "Release: " + Build.VERSION.RELEASE + ", "
+        + "Release: " + Build.VERSION.RELEASE_OR_CODENAME + ", "
         + "Brand: " + Build.BRAND + ", "
         + "Device: " + Build.DEVICE + ", "
         + "Id: " + Build.ID + ", "

webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/BuildInfo.java

@@ -43,7 +43,7 @@ public final class BuildInfo {
   }
 
   public static String getBuildRelease() {
-    return Build.VERSION.RELEASE;
+    return Build.VERSION.RELEASE_OR_CODENAME;
   }
 
   public static String getSdkVersion() {

webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioUtils.java

@@ -182,7 +182,7 @@ public final class WebRtcAudioUtils {
   // Information about the current build, taken from system properties.
   public static void logDeviceInfo(String tag) {
     Logging.d(tag, "Android SDK: " + Build.VERSION.SDK_INT + ", "
-        + "Release: " + Build.VERSION.RELEASE + ", "
+        + "Release: " + Build.VERSION.RELEASE_OR_CODENAME + ", "
         + "Brand: " + Build.BRAND + ", "
         + "Device: " + Build.DEVICE + ", "
         + "Id: " + Build.ID + ", "