tools/progress: Add finish and abort functions

We have external progress handlers which would like to implement these
functions, in order to update the screen upon completion or error.

Change-Id: I2df4654d5e2092407a83d2c8bbb020dcce84ac50
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/tools/progress.cpp b/tools/progress.cpp
index aafb1de..68b31cc 100644
--- a/tools/progress.cpp
+++ b/tools/progress.cpp
@@ -39,4 +39,10 @@
     currentBytes = 0;
 }
 
+void ProgressStdoutIndicator::finish()
+{}
+
+void ProgressStdoutIndicator::abort()
+{}
+
 } // namespace host_tool