Fix media_cas_proxy_sdk build issue.

Add example binary for testing building the SDK after 'git clone' from our repo.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=227583629

protos/public/license_protocol.proto

@@ -191,6 +191,8 @@ message License {
       optional HdcpSrmRule hdcp_srm_rule = 3 [default = HDCP_SRM_RULE_NONE];
       // Optional requirement to indicate analog output is not allowed.
       optional bool disable_analog_output = 4 [default = false];
+      // Optional requirement to indicate digital output is not allowed.
+      optional bool disable_digital_output = 5 [default = false];
     }
 
     message VideoResolutionConstraint {
@@ -273,6 +275,7 @@ message License {
 enum ProtocolVersion {
   VERSION_2_0 = 20;
   VERSION_2_1 = 21;
+  VERSION_2_2 = 22;
 }
 
 message LicenseRequest {