Fix `adb logcat` return code.

`adb shell logcat` works, and `adb logcat` should too.

Bug: http://b/110202648
Test: suspended the logd process and manually removed the socket
Change-Id: If14de7c2eb178c7b4210d6bdb44df084615db33a
diff --git a/adb/client/commandline.h b/adb/client/commandline.h
index 36cd798..3d10030 100644
--- a/adb/client/commandline.h
+++ b/adb/client/commandline.h
@@ -92,7 +92,7 @@
 // resulting output.
 // if |callback| is non-null, stdout/stderr output will be handled by it.
 int send_shell_command(
-    const std::string& command, bool disable_shell_protocol,
-    StandardStreamsCallbackInterface* callback = &DEFAULT_STANDARD_STREAMS_CALLBACK);
+        const std::string& command, bool disable_shell_protocol = false,
+        StandardStreamsCallbackInterface* callback = &DEFAULT_STANDARD_STREAMS_CALLBACK);
 
 #endif  // COMMANDLINE_H