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.hpp b/tools/progress.hpp
index f884d62..2027faf 100644
--- a/tools/progress.hpp
+++ b/tools/progress.hpp
@@ -15,6 +15,8 @@
      */
     virtual void updateProgress(std::int64_t bytes) = 0;
     virtual void start(std::int64_t bytes) = 0;
+    virtual void finish() = 0;
+    virtual void abort() = 0;
 };
 
 /**
@@ -29,6 +31,8 @@
 
     void updateProgress(std::int64_t bytes) override;
     void start(std::int64_t bytes) override;
+    void finish() override;
+    void abort() override;
 
   private:
     std::int64_t totalBytes = 0;