This patch captures and serializes all output being written by the
command line driver, including the lldb prompt being output by
editline, the asynchronous process output & error messages, and
asynchronous messages written by target stop-hooks.

As part of this it introduces a new Stream class,
StreamAsynchronousIO.  A StreamAsynchronousIO object is created with a
broadcaster, who will eventually broadcast the stream's data for a
listener to handle, and an event type indicating what type of event
the broadcaster will broadcast.  When the Write method is called on a
StreamAsynchronousIO object, the data is appended to an internal
string.  When the Flush method is called on a StreamAsynchronousIO
object, it broadcasts it's data string and clears the string.

Anything in lldb-core that needs to generate asynchronous output for
the end-user should use the StreamAsynchronousIO objects.

I have also added a new notification type for InputReaders, to let
them know that a asynchronous output has been written. This is to
allow the input readers to, for example, refresh their prompts and
lines, if desired.  I added the case statements to all the input
readers to catch this notification, but I haven't added any code for
handling them yet (except to the IOChannel input reader).



git-svn-id: https://llvm.org/svn/llvm-project/llvdb/trunk@130721 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Commands/CommandObjectExpression.cpp b/source/Commands/CommandObjectExpression.cpp
index ed7824b..fa578f4 100644
--- a/source/Commands/CommandObjectExpression.cpp
+++ b/source/Commands/CommandObjectExpression.cpp
@@ -205,6 +205,9 @@
     case eInputReaderDeactivate:
         break;
 
+    case eInputReaderAsynchronousOutputWritten:
+        break;
+        
     case eInputReaderGotToken:
         ++cmd_object_expr->m_expr_line_count;
         if (bytes && bytes_len)