Add tests for setup-bcb and clear-bcb via uncrypt.

Bug: http://b/33534933
Test: recovery_component_test passes (and fails on buggy build due to
      the CL in [1]).

[1]: commit 7e31f421a514da09b90e46dbd642a5e9b16e0003

Change-Id: I120498048ec1db8f9fcbb3cf135c05d3a48cfcdf
diff --git a/uncrypt/uncrypt.cpp b/uncrypt/uncrypt.cpp
index 38b25ab..4ac516d 100644
--- a/uncrypt/uncrypt.cpp
+++ b/uncrypt/uncrypt.cpp
@@ -530,7 +530,7 @@
     std::string content;
     content.resize(length);
     if (!android::base::ReadFully(socket, &content[0], length)) {
-        PLOG(ERROR) << "failed to read the length";
+        PLOG(ERROR) << "failed to read the message";
         return false;
     }
     LOG(INFO) << "  received command: [" << content << "] (" << content.size() << ")";